{ "spore": "profile", "id": "molybdenum-carbide", "spore_version": "0.2", "family": "carbide-nitride-boride-ceramics", "name": "Molybdenum carbide", "abbreviation": "Mo2C", "role": "hard refractory carbide for wear parts and tool materials, and a noble-metal-free electrocatalyst for hydrogen evolution", "category": "ceramics", "type": "carbides", "summary": "Molybdenum carbide is a molybdenum-carbon compound. Wikipedia lists two formulas, Mo2C and MoC, and at least three phases, including beta-Mo2C and gamma-MoC. A supplier SDS (revision 30-Mar-2024) gives a melting point of 2687 °C for Mo2C, and two vendors give a density of 9.18 g/cm3 and 9.20 g/cm3. In Hussain et al. (2019), chemically reduced Mo2C nanoparticles on nickel foam reach 10 mA cm-2 at -134 mV in 0.5 M H2SO4 and at -116 mV in 1 M KOH, for hydrogen evolution. A 2002 Washington State University thesis reports an oxidation onset near 600 °C in steam or CO2. The supplier SDS classes the powder as not hazardous under the 2012 OSHA standard, but says its toxicological properties have not been fully investigated. Molybdenum diboride (MoB2) is a related molybdenum boride, mentioned here only for context and not profiled in this file.\n", "best_for": "Hard, high-melting carbide powder for wear parts and tool materials (vendor claims), and noble-metal-free hydrogen-evolution electrocatalysis in both acid and alkaline water (Hussain et al. 2019)", "weakest_at": "Hardness, thermal conductivity and expansion of pure Mo2C are not sourced in this file. The powder oxidises in steam or CO2 from about 600 °C, and it is a dust-forming powder that the SDS says to keep from dispersing", "identity": { "formula": "Mo2C, molybdenum carbide: a 2:1 molybdenum-carbon compound. MoC is the other composition that Wikipedia lists for the same system", "cas": "12069-89-5", "designations": [], "source": "sam-mo2c-sds", "where": "Section 3 Composition, Molybdenum carbide (Mo2C), CAS No 12069-89-5" }, "tags": { "environments": [], "stresses": [ "extreme-heat" ], "applications": [ "mechanisms", "cryogenic-fuel" ] }, "properties": [ { "benchmark": "density", "label": "Density, Mo2C powder (SAMaterials product page)", "value": 9.18, "bound": "exact", "unit": "g/cm3", "scope": "material", "conditions": { "form": "powder, purity more than 99.5 percent as printed", "basis": "vendor specification table" }, "method": "Vendor specification value, read from the product specification table. The vendor does not name a measurement method.", "status": "ground", "source": "sam-mo2c-product", "where": "Product specification table, Density (g/cm3) row", "source_detail": { "title": "SAMaterials, Micro molybdenum carbide (Mo2C) powder, product page", "url": "https://samaterials.com/micro-nano-materials/201-micro-molybdenum-carbide.html", "kind": "datasheet", "license": "vendor product page, cited not reproduced" } }, { "benchmark": "density", "label": "Density, Mo2C micron powder (Nanografi)", "value": 9.2, "bound": "exact", "unit": "g/cm3", "scope": "material", "conditions": { "form": "micron powder, average particle size 2.6 µm as printed", "basis": "vendor specification list" }, "method": "Vendor specification value. It differs from the 9.18 g/cm3 printed by the other vendor, and no method is given by either.", "status": "ground", "source": "nanografi-mo2c", "where": "Product specification list, density row", "source_detail": { "title": "Nanografi, Molybdenum carbide (Mo2C) micron powder, product page", "url": "https://shop.nanografi.com/microparticles/molybdenum-carbide-mo2c-micron-powder-purity-99-5-size-2-6-m-hexagonal/", "kind": "datasheet", "license": "vendor product page, cited not reproduced" } }, { "benchmark": "melting_point", "label": "Melting point, Mo2C (SDS)", "value": 2687, "bound": "exact", "unit": "°C", "scope": "material", "conditions": { "basis": "as printed in SDS section 9" }, "method": "Supplier SDS value, printed as 2687 °C. The Fahrenheit equivalent on the same row is not used.", "status": "ground", "source": "sam-mo2c-sds", "where": "Section 9 Physical and chemical properties, Melting Point/Range row", "source_detail": { "title": "Stanford Advanced Materials, Safety data sheet, Molybdenum carbide, revision 3 (30-Mar-2024)", "url": "https://www.samaterials.com/tds/sc/1752570513-ST0225.pdf", "kind": "datasheet", "license": "supplier safety data sheet, cited not reproduced" } }, { "benchmark": "melting_point", "label": "Melting point, Mo2C micron powder (Nanografi)", "value": 2690, "bound": "exact", "unit": "°C", "scope": "material", "conditions": { "basis": "as printed on the vendor specification list" }, "method": "Vendor specification value, printed as 2690.0 °C. It is 3 °C above the SDS value of 2687 °C, and the two are kept side by side.", "status": "ground", "source": "nanografi-mo2c", "where": "Product specification list, melting point row", "source_detail": { "title": "Nanografi, Molybdenum carbide (Mo2C) micron powder, product page", "url": "https://shop.nanografi.com/microparticles/molybdenum-carbide-mo2c-micron-powder-purity-99-5-size-2-6-m-hexagonal/", "kind": "datasheet", "license": "vendor product page, cited not reproduced" } }, { "benchmark": "tafel_slope", "label": "Tafel slope, Mo2C in 0.5 M H2SO4", "value": 83, "bound": "exact", "unit": "mV dec-1", "scope": "material", "conditions": { "electrolyte": "0.5 M H2SO4", "form": "chemically reduced Mo2C nanoparticles on nickel foam" }, "method": "Tafel plot from the linear sweep data. The authors read the Volmer-Heyrovsky step from this slope.", "status": "ground", "source": "hussain-2019", "where": "Table 1, row 0.5 M H2SO4, Mo2C, Tafel slope column; text on the Tafel slope", "source_detail": { "title": "Hussain et al., Synthesis of Mo2C and W2C nanoparticle electrocatalysts for the efficient hydrogen evolution reaction in alkali and acid electrolytes, Frontiers in Chemistry 7:716 (2019)", "url": "https://www.frontiersin.org/articles/10.3389/fchem.2019.00716/pdf", "kind": "paper", "license": "open access, cited not reproduced" } }, { "benchmark": "tafel_slope", "label": "Tafel slope, Mo2C in 1 M KOH", "value": 65, "bound": "exact", "unit": "mV dec-1", "scope": "material", "conditions": { "electrolyte": "1 M KOH", "form": "chemically reduced Mo2C nanoparticles on nickel foam" }, "method": "Tafel plot from the linear sweep data, as tabulated by the authors.", "status": "ground", "source": "hussain-2019", "where": "Table 1, row 1 M KOH, Mo2C, Tafel slope column", "source_detail": { "title": "Hussain et al., Synthesis of Mo2C and W2C nanoparticle electrocatalysts for the efficient hydrogen evolution reaction in alkali and acid electrolytes, Frontiers in Chemistry 7:716 (2019)", "url": "https://www.frontiersin.org/articles/10.3389/fchem.2019.00716/pdf", "kind": "paper", "license": "open access, cited not reproduced" } }, { "benchmark": "exchange_current_density", "label": "Exchange current density, Mo2C in 0.5 M H2SO4", "value": 0.131, "bound": "exact", "unit": "mA cm-2", "scope": "material", "conditions": { "electrolyte": "0.5 M H2SO4", "form": "chemically reduced Mo2C nanoparticles on nickel foam" }, "method": "Value tabulated by the authors, read from the exchange current density column.", "status": "ground", "source": "hussain-2019", "where": "Table 1, row 0.5 M H2SO4, Mo2C, exchange current density column", "source_detail": { "title": "Hussain et al., Synthesis of Mo2C and W2C nanoparticle electrocatalysts for the efficient hydrogen evolution reaction in alkali and acid electrolytes, Frontiers in Chemistry 7:716 (2019)", "url": "https://www.frontiersin.org/articles/10.3389/fchem.2019.00716/pdf", "kind": "paper", "license": "open access, cited not reproduced" } }, { "benchmark": "exchange_current_density", "label": "Exchange current density, Mo2C in 1 M KOH", "value": 0.846, "bound": "exact", "unit": "mA cm-2", "scope": "material", "conditions": { "electrolyte": "1 M KOH", "form": "chemically reduced Mo2C nanoparticles on nickel foam" }, "method": "Value tabulated by the authors, read from the exchange current density column.", "status": "ground", "source": "hussain-2019", "where": "Table 1, row 1 M KOH, Mo2C, exchange current density column", "source_detail": { "title": "Hussain et al., Synthesis of Mo2C and W2C nanoparticle electrocatalysts for the efficient hydrogen evolution reaction in alkali and acid electrolytes, Frontiers in Chemistry 7:716 (2019)", "url": "https://www.frontiersin.org/articles/10.3389/fchem.2019.00716/pdf", "kind": "paper", "license": "open access, cited not reproduced" } }, { "benchmark": "turnover_frequency", "label": "Turnover frequency, Mo2C at -134 mV in acid", "value": 0.005, "bound": "exact", "unit": "H2 s-1", "scope": "material", "conditions": { "electrolyte": "0.5 M H2SO4", "overpotential": "-134 mV" }, "method": "Calculated by the authors from the number of active sites. It is a per-site rate, not a mass rate.", "status": "ground", "source": "hussain-2019", "where": "Text paragraph after Table 1, TOF values of Mo2C", "source_detail": { "title": "Hussain et al., Synthesis of Mo2C and W2C nanoparticle electrocatalysts for the efficient hydrogen evolution reaction in alkali and acid electrolytes, Frontiers in Chemistry 7:716 (2019)", "url": "https://www.frontiersin.org/articles/10.3389/fchem.2019.00716/pdf", "kind": "paper", "license": "open access, cited not reproduced" } }, { "benchmark": "turnover_frequency", "label": "Turnover frequency, Mo2C at -116 mV in alkaline", "value": 0.037, "bound": "exact", "unit": "H2 s-1", "scope": "material", "conditions": { "electrolyte": "1 M KOH", "overpotential": "-116 mV" }, "method": "Calculated by the authors from the number of active sites. It is a per-site rate, not a mass rate.", "status": "ground", "source": "hussain-2019", "where": "Text paragraph after Table 1, TOF values of Mo2C", "source_detail": { "title": "Hussain et al., Synthesis of Mo2C and W2C nanoparticle electrocatalysts for the efficient hydrogen evolution reaction in alkali and acid electrolytes, Frontiers in Chemistry 7:716 (2019)", "url": "https://www.frontiersin.org/articles/10.3389/fchem.2019.00716/pdf", "kind": "paper", "license": "open access, cited not reproduced" } }, { "benchmark": "particle_size", "label": "Particle size D50, Mo2C powder (SAMaterials product page)", "value": 0.5, "value_high": 3, "bound": "exact", "unit": "µm", "scope": "material", "conditions": { "basis": "APS (D50) as printed by the vendor" }, "method": "Vendor specification range, printed as 0.5-3 µm. This is the vendor micron powder, not the Nanografi sample.", "status": "ground", "source": "sam-mo2c-product", "where": "Product specification table, APS (D50) row", "source_detail": { "title": "SAMaterials, Micro molybdenum carbide (Mo2C) powder, product page", "url": "https://samaterials.com/micro-nano-materials/201-micro-molybdenum-carbide.html", "kind": "datasheet", "license": "vendor product page, cited not reproduced" } } ], "corrosion": [ { "environment": "Steam or carbon dioxide at high temperature, up to 850 °C and up to 8 bar", "headline": "In steam or CO2, Mo2C oxidation starts at about 600 °C", "effect": "Darujati (2002) reports an oxidation onset of about 600 °C in either steam or CO2. Above 750 °C the paper describes thermal decomposition and then oxidation of the Mo metal. CO2 is the stronger oxidant at the higher temperatures. The rating moderate is the assistant's judgement from this onset; the paper gives no rating.", "rating": "moderate", "conditions": { "atmosphere": "steam or CO2", "pressure": "up to 8 bar", "temperature": "up to 850 °C" }, "source": "darujati-2002", "where": "Abstract" }, { "environment": "Air or storage at room temperature", "headline": "The SDS calls Mo2C stable under normal conditions; no air oxidation rate was read", "effect": "The SDS section 10 says the product is stable under normal conditions, with no known reactive hazard, and lists oxidising agents as incompatible. No onset temperature or mass gain for Mo2C powder in air was found in a source read in this run, so the rating is unknown.", "rating": "unknown", "conditions": { "atmosphere": "air", "temperature": "normal storage" }, "source": "sam-mo2c-sds", "where": "Section 10 Stability and reactivity" }, { "environment": "Oxygen-bearing surfaces during deoxygenation (DFT on the Mo2C(100) surface)", "headline": "Oxygen deposited on Mo2C can form oxycarbides", "effect": "Likith et al. (2018) state that oxygen deposited during deoxygenation reactions may alter the carbide structure and form oxycarbides. Their surface calculations suggest that oxygen is not stable under the top Mo layer of the Mo2C(100) surface. The rating is unknown because the paper gives no corrosion rate.", "rating": "unknown", "conditions": { "basis": "DFT surface calculations on Mo2C(100)" }, "source": "likith-2018", "where": "Abstract" } ], "risks": { "hazards": [ { "text": "Stanford Advanced Materials SDS, revision 30-Mar-2024: not considered hazardous under the 2012 OSHA Hazard Communication Standard. Label elements none required. Hazards not otherwise classified none identified.", "ghs": [], "source": "sam-mo2c-sds", "where": "Section 2 Hazard(s) identification" }, { "text": "The SDS states that the toxicological properties have not been fully investigated. Irritation and sensitization: no information available.", "ghs": [], "source": "sam-mo2c-sds", "where": "Section 11 Toxicological information" }, { "text": "Exposure guideline printed for Mo2C: ACGIH TLV TWA 10 mg/m3, a second TWA of 3 mg/m3 on the same row, and NIOSH IDLH 5000 mg/m3. The table does not label the second TWA.", "ghs": [], "source": "sam-mo2c-sds", "where": "Section 8 Exposure guidelines table" } ], "failure_risks": [ { "mode": "Oxidation of the carbide at high temperature", "trigger": "Heating in steam or CO2 above about 600 °C", "consequence": "Conversion of the carbide to oxide. Above 750 °C the paper describes decomposition followed by oxidation of the Mo metal.", "severity": "moderate", "source": "darujati-2002", "where": "Abstract" }, { "mode": "Reaction with oxidising agents", "trigger": "Contact with an oxidising agent", "consequence": "The SDS lists oxidising agents as incompatible. Hazardous decomposition products are molybdenum oxides.", "severity": "low", "source": "sam-mo2c-sds", "where": "Section 7 Storage and Section 10 Stability and reactivity" }, { "mode": "Oxycarbide formation on the surface", "trigger": "Oxygen deposited during deoxygenation reactions", "consequence": "May alter the carbide structure and form oxycarbides, per Likith et al. (2018). The effect on performance is not quantified in the abstract.", "severity": "low", "source": "likith-2018", "where": "Abstract" } ], "side_effects": [], "handling": [ { "text": "Keep the powder from dispersing. The SDS says to avoid dust formation during handling and clean-up, and to ventilate the area.", "source": "sam-mo2c-sds", "where": "Sections 6 and 7 Accidental release and Handling" }, { "text": "Store in a dry, cool and well-ventilated place with the containers tightly closed, away from oxidising agents (SDS section 7).", "source": "sam-mo2c-sds", "where": "Section 7 Storage" }, { "text": "Wear eye protection and gloves. The SDS lists a particle filter for respiratory protection and says no protective equipment is needed under normal use conditions.", "source": "sam-mo2c-sds", "where": "Section 8 Personal protection" } ], "mitigations": [] }, "uses": [ { "application": "mechanisms", "device": "Superhard tool material and wear-resistant parts", "example": "The vendor product page lists Mo2C powder as a superhard tool material and a wear-resistant material. The page gives no test numbers, so this is a vendor claim only.", "source": "sam-mo2c-product", "where": "Applications section" }, { "application": "cryogenic-fuel", "device": "Electrocatalyst for hydrogen evolution in water electrolysis", "example": "Chemically reduced Mo2C nanoparticles on nickel foam reach 10 mA cm-2 at -134 mV in 0.5 M H2SO4 and at -116 mV in 1 M KOH. This is Earth-side water electrolysis. The application tag cryogenic-fuel is the closest item in the allowed list, not a flight use.", "source": "hussain-2019", "where": "Table 1 and abstract" } ], "supply": [ { "subject": "Molybdenum (feedstock for the molybdenum half of Mo2C)", "abundance": "Not in the USGS PP 1802-A Table A1 crustal abundance list, which has no molybdenum row. The same table lists carbon at 200 ppm.", "producers": [ { "country": "China", "share_percent": 37.3, "year": 2025 }, { "country": "Chile", "share_percent": 16.2, "year": 2025 }, { "country": "United States", "share_percent": 15.4, "year": 2025 }, { "country": "Peru", "share_percent": 15, "year": 2025 }, { "country": "Mexico", "share_percent": 6.5, "year": 2025 } ], "critical_lists": [], "recycling": "USGS 2026: molybdenum is recycled as a component of catalysts, ferrous scrap and superalloy scrap.", "substitutes": [ "USGS 2026: little substitution for molybdenum in steels and cast irons. Potential substitutes in alloy steels include boron, chromium, niobium and vanadium, and tungsten in tool steels." ], "source": "usgs-mcs2026-molybdenum", "where": "World Mine Production and Reserves table, 2025e column (world total 260,000 t). Shares calculated by this file from the printed tonnage over that total. Recycling and Substitutes paragraphs. Abundance from USGS PP 1802-A Table A1." } ], "media": [], "documents": [ { "title": "Stanford Advanced Materials, Safety data sheet, Molybdenum carbide (CAS 12069-89-5), revision 3, 30-Mar-2024", "type": "sds", "url": "https://www.samaterials.com/tds/sc/1752570513-ST0225.pdf", "year": 2024 }, { "title": "SAMaterials, Micro molybdenum carbide (Mo2C) powder, product page", "type": "datasheet", "url": "https://samaterials.com/micro-nano-materials/201-micro-molybdenum-carbide.html" }, { "title": "Nanografi, Molybdenum carbide (Mo2C) micron powder, purity 99.5, size 2.6 µm, hexagonal, product page", "type": "datasheet", "url": "https://shop.nanografi.com/microparticles/molybdenum-carbide-mo2c-micron-powder-purity-99-5-size-2-6-m-hexagonal/" }, { "title": "Hussain, Vikraman, Feroze, Song, An, Kim, Chun and Jung, Synthesis of Mo2C and W2C nanoparticle electrocatalysts for the efficient hydrogen evolution reaction in alkali and acid electrolytes, Frontiers in Chemistry 7:716 (2019)", "type": "paper", "url": "https://www.frontiersin.org/articles/10.3389/fchem.2019.00716/pdf", "year": 2019 }, { "title": "Darujati, thesis on the effect of reforming gases on molybdenum carbide oxidation, Washington State University (2002)", "type": "report", "url": "https://rex.libraries.wsu.edu/esploro/outputs/graduate/The-effect-of-reforming-gases-on/99900525277201842", "year": 2002 }, { "title": "Likith et al., Thermodynamic stability of molybdenum oxycarbides formed from orthorhombic Mo2C in oxygen-rich environments, J. Phys. Chem. C 122(2), 1223-1233 (2018), arXiv:1803.11546", "type": "paper", "url": "https://arxiv.org/abs/1803.11546", "year": 2018 }, { "title": "USGS Mineral Commodity Summaries 2026, Molybdenum", "type": "report", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf", "year": 2026 }, { "title": "USGS Professional Paper 1802-A, Critical Mineral Resources of the United States, Table A1 (crustal abundances)", "type": "report", "url": "https://pubs.usgs.gov/pp/1802/a/pp1802a.pdf", "year": 2017 }, { "title": "NIST Atomic Weights and Isotopic Compositions, molybdenum (atomic number 42, standard atomic weight 95.95(1))", "type": "database", "url": "https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Mo&all=all&ascii=html" }, { "title": "NIST Atomic Weights and Isotopic Compositions, carbon (atomic number 6, standard atomic weight printed as [12.0096, 12.0116])", "type": "database", "url": "https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=C&all=all&ascii=html" }, { "title": "Wikipedia, Molybdenum carbide (composition, phases and history only)", "type": "database", "url": "https://en.wikipedia.org/wiki/Molybdenum_carbide" } ], "gaps": [ "Hardness of pure Mo2C: no measured value read. The only Mo-based coating values found were for Mo2BC and Mo-B-C films, which are different phases, so they are not used. Wikipedia gives no hardness figure.", "Thermal conductivity, coefficient of thermal expansion and elastic modulus of monolithic Mo2C: no fetched source with a printed value. The Mo2C-SiC co-sputtering paper (EPJ Applied Physics 2016) returned HTTP 403, so its values were not read.", "MoC (the gamma phase): no MoC-specific property was read from a fetched source. Wikipedia names the composition and says the gamma phase has the same structure as tungsten carbide, which is composition and history only and is not used as a property.", "Density and melting point rely on vendor pages and one SDS only. The Wikipedia infobox prints 8.90 g/cm3 and 2687 °C; the brief allows Wikipedia for composition and history only, so the 8.90 density is not used. PubChem returned a browser check and gave no value.", "Designations (UNS, EN, DIN, JIS, ASTM and similar): no fetched source printed a designation for this material. None are listed.", "Catalysis use: the 2010 AIChE abstract on Pt/Mo2C catalysts returned HTTP 403. The catalysis claim here (alkane isomerisation) is a vendor statement only. No hydrotreating, CO2 hydrogenation or Levy and Boudart source was read.", "Hard-coating use: no fetched source gives a Mo2C coating result with a number. The vendor page calls the powder a wear-resistant material with no test data.", "Air oxidation of Mo2C powder: no onset temperature or mass gain in air was found in a source read in this run. The 600 °C onset is for steam and CO2 only.", "Production route (carburisation or carbothermal reduction): no fetched source. Carbon feedstock is therefore not recorded beyond the formula.", "Critical-mineral status of molybdenum (USGS 2025 critical list, EU critical raw materials list): not read in this run, so critical_lists is empty. The USGS MCS 2026 molybdenum PDF text read in this run does not mention the critical list.", "Molybdenum crustal abundance: no molybdenum row in USGS PP 1802-A Table A1 (carbon is listed at 200 ppm in that table).", "Environments: no source read supports a space environment tag, so tags.environments is empty.", "Hazards: only the SAMaterials SDS was read. American Elements (page returned 404) and other supplier SDS pages were searched but not read. No GHS hazard statement was found for Mo2C in a fetched page.", "Property names not in property-canon.yaml: tafel_slope, exchange_current_density, turnover_frequency and particle_size. Values are kept in the units the authors print.", "The two density values (9.18 and 9.20 g/cm3) and the two melting values (2687 and 2690 °C) differ between vendors. Both are kept; no single value is chosen.", "The two HER overpotentials (-134 mV in 0.5 M H2SO4 and -116 mV in 1 M KOH, Hussain et al. 2019 Table 1) are printed with a Unicode minus sign, so the value check cannot match them. They are kept in the uses and story text, and removed from properties until the check reads that glyph.", "Atomic weight of molybdenum: NIST prints 95.95(1), and 95.95 is used with the parenthesised uncertainty dropped. Carbon is printed as an interval, [12.0096, 12.0116]; the lower bound is used in the recipe." ], "story": { "why": "Molybdenum carbide is a dense, high-melting carbide with two sourced uses. A vendor describes the powder as a superhard tool material and a wear-resistant material, with no test data. Hussain et al. (2019) show that chemically reduced Mo2C nanoparticles on nickel foam are an active, noble-metal-free electrocatalyst for hydrogen evolution in both acid and alkaline water. Its composition and phase names come from Wikipedia, which is used for composition and history only.", "uses": [ { "where": "Wear and tool materials", "line": "A vendor page lists Mo2C powder as a superhard tool material and a wear-resistant material. The page gives no test numbers." }, { "where": "Hydrogen-evolution electrocatalyst", "line": "In 0.5 M H2SO4 the Mo2C catalyst reaches 10 mA cm-2 at -134 mV, with a Tafel slope of 83 mV dec-1. In 1 M KOH it reaches the same current density at -116 mV, with a Tafel slope of 65 mV dec-1 (Hussain et al. 2019)." }, { "where": "Catalysis in general", "line": "A vendor page says Mo2C is used as a catalyst for reactions involving hydrogen, such as alkane isomerisation. No primary source for this use was read in this run." } ], "can_do": [ { "label": "Melting", "line": "The SDS gives a melting point of 2687 °C. The Nanografi micron powder is listed at 2690 °C. The two are kept side by side.", "benchmark": "melting_point", "scope": "material" }, { "label": "Density", "line": "Two vendors list 9.18 g/cm3 and 9.20 g/cm3. No measurement method is given by either vendor.", "benchmark": "density", "scope": "material" }, { "label": "Hydrogen evolution", "line": "At 10 mA cm-2 the overpotential is -134 mV in 0.5 M H2SO4 and -116 mV in 1 M KOH, with the catalyst on nickel foam (Hussain et al. 2019). These depend on electrolyte and substrate.", "benchmark": "tafel_slope", "scope": "material" } ], "compare": "The Mo2C densities from two vendors (9.18 and 9.20 g/cm3) are higher than the density of titanium carbide in its own profile, and the Mo2C melting point (2687 °C in the SDS) is also high for a carbide. The HER overpotential is only meaningful against other catalysts in the same electrolyte and on the same substrate, so no cross-catalyst ranking is made here. Molybdenum diboride (MoB2) is a related molybdenum boride, mentioned here for context only and not profiled in this file.", "compare_rows": [ { "label": "Density", "benchmark": "density", "scope": "material" }, { "label": "Melting point", "benchmark": "melting_point", "scope": "material" }, { "label": "Tafel slope in 0.5 M H2SO4", "benchmark": "tafel_slope", "scope": "material" } ], "handling": [ "Dust: keep the powder from dispersing. The SDS says to avoid dust formation.", "Oxidants: keep away from oxidising agents, which the SDS lists as incompatible.", "Heat: in steam or CO2 the carbide oxidises from about 600 °C, so plan for oxide formation in hot service." ], "good_for": [ "Hard, high-melting powder for wear parts and tool materials, as claimed by the vendor. No test data are sourced here.", "Noble-metal-free electrocatalysis for hydrogen evolution in acid and alkaline water, per Hussain et al. 2019." ], "watch_out": [ "Oxidation in steam or CO2 from about 600 °C, and oxycarbide formation under oxygen-bearing conditions (Likith et al. 2018).", "The SDS does not fully investigate toxicology, and the dust must be kept down even though the powder is not classed as hazardous.", "China imposed export controls on molybdenum powders in February 2025 (USGS MCS 2026). This affects supply of the feedstock, not the Mo2C itself.", "Hardness, thermal conductivity and expansion of pure Mo2C are not settled here." ], "verdict": "Molybdenum carbide is a high-melting, dense carbide with a sourced hydrogen-evolution record and a vendor-stated use as a tool and wear material. Its hardness, thermal properties and air oxidation kinetics are not sourced in this file. The powder is classed as not hazardous, but its toxicology is not fully investigated and it oxidises from about 600 °C in steam or CO2.", "recipe": { "line": "Mo2C is a molybdenum-carbon compound with two molybdenum atoms and one carbon atom per formula unit. Wikipedia lists MoC and Mo2C as the two compositions of this system, with at least three phases. The synthesis route is not sourced in this file.", "parts": [ { "name": "Molybdenum", "symbol": "Mo", "role": "The metal sublattice. The NIST standard atomic weight is 95.95 with an uncertainty of 1 in the last digit.", "atoms": 2, "atomic_weight": 95.95 }, { "name": "Carbon", "symbol": "C", "role": "Sits in the interstitial sites of the metal lattice. NIST prints the standard atomic weight as the interval 12.0096 to 12.0116, and the lower bound is used.", "atoms": 1, "atomic_weight": 12.0096 } ] }, "risk_groups": [ { "title": "For people", "lead": "The supplier SDS classes the powder as not hazardous under OSHA 2012, but the toxicology has not been fully investigated. Treat the dust as the main handling concern.", "points": [ { "label": "Dust", "line": "The SDS says to avoid dust formation. It lists an ACGIH TLV of 10 mg/m3 as a TWA." }, { "label": "Toxicology", "line": "The SDS states that the toxicological properties have not been fully investigated, and gives no irritation or sensitization data." } ], "level": 0, "verdict": "Not classed hazardous, but dust must be kept down" }, { "title": "If the powder heats in steam or CO2", "lead": "These numbers come from the Darujati thesis on Mo2C oxidation in steam and CO2.", "points": [ { "label": "Onset", "line": "Oxidation starts at about 600 °C in either steam or CO2. Above 750 °C the paper describes decomposition and then oxidation of the Mo metal." } ] } ] }, "updated": "2026-10-26", "review": { "status": "draft", "method": "assistant", "checked_values": 11, "unreachable": 3, "caveats": 6, "note": "Written in this run from pages read in this run: the SAMaterials SDS (revision 30-Mar-2024), the SAMaterials product page, the Nanografi product page, Hussain et al. 2019 Table 1 and the TOF paragraph, the Darujati 2002 WSU abstract, the Likith et al. 2018 arXiv abstract, the USGS MCS 2026 molybdenum PDF, the USGS PP 1802-A PDF, NIST atomic weights for Mo and C, and Wikipedia for composition and history only. Unreachable: PubChem (browser check), AIChE 2010 abstract (HTTP 403), EPJ Applied Physics 2016 abstract (HTTP 403)." }, "sources": { "sam-mo2c-sds": { "title": "Stanford Advanced Materials, Safety data sheet, Molybdenum carbide, revision 3 (30-Mar-2024)", "url": "https://www.samaterials.com/tds/sc/1752570513-ST0225.pdf", "kind": "datasheet", "license": "supplier safety data sheet, cited not reproduced" }, "sam-mo2c-product": { "title": "SAMaterials, Micro molybdenum carbide (Mo2C) powder, product page", "url": "https://samaterials.com/micro-nano-materials/201-micro-molybdenum-carbide.html", "kind": "datasheet", "license": "vendor product page, cited not reproduced" }, "nanografi-mo2c": { "title": "Nanografi, Molybdenum carbide (Mo2C) micron powder, product page", "url": "https://shop.nanografi.com/microparticles/molybdenum-carbide-mo2c-micron-powder-purity-99-5-size-2-6-m-hexagonal/", "kind": "datasheet", "license": "vendor product page, cited not reproduced" }, "hussain-2019": { "title": "Hussain et al., Synthesis of Mo2C and W2C nanoparticle electrocatalysts for the efficient hydrogen evolution reaction in alkali and acid electrolytes, Frontiers in Chemistry 7:716 (2019)", "url": "https://www.frontiersin.org/articles/10.3389/fchem.2019.00716/pdf", "kind": "paper", "license": "open access, cited not reproduced" }, "darujati-2002": { "title": "Darujati, Washington State University thesis (2002), effect of reforming gases on molybdenum carbide oxidation", "url": "https://rex.libraries.wsu.edu/esploro/outputs/graduate/The-effect-of-reforming-gases-on/99900525277201842", "kind": "report", "license": "university repository, cited not reproduced" }, "likith-2018": { "title": "Likith et al., Thermodynamic stability of molybdenum oxycarbides formed from orthorhombic Mo2C in oxygen-rich environments, J. Phys. Chem. C 122(2) (2018), arXiv:1803.11546", "url": "https://arxiv.org/abs/1803.11546", "kind": "paper", "license": "arXiv preprint, cited not reproduced" }, "usgs-mcs2026-molybdenum": { "title": "USGS Mineral Commodity Summaries 2026, Molybdenum", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf", "kind": "report", "license": "public domain (USGS)" }, "usgs-pp1802a": { "title": "USGS Professional Paper 1802-A, Critical Mineral Resources of the United States, Table A1 (crustal abundances)", "url": "https://pubs.usgs.gov/pp/1802/a/pp1802a.pdf", "kind": "report", "license": "public domain (USGS)" }, "nist-mo": { "title": "NIST, Atomic weights and isotopic compositions for all elements, molybdenum", "url": "https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Mo&all=all&ascii=html", "kind": "database", "license": "NIST public data" }, "nist-c": { "title": "NIST, Atomic weights and isotopic compositions for all elements, carbon", "url": "https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=C&all=all&ascii=html", "kind": "database", "license": "NIST public data" }, "wikipedia-mo2c": { "title": "Wikipedia, Molybdenum carbide (composition, phases and history only)", "url": "https://en.wikipedia.org/wiki/Molybdenum_carbide", "kind": "web", "license": "CC-BY-SA 4.0" } }, "license": "CC-BY-4.0", "url": "https://spacemushroom.com/profiles/molybdenum-carbide/" }