Mixed close packed cobalt molybdenum nitrides as non-noble metal electrocatalysts for the hydrogen evolution reaction

Journal Article · Tue Jan 01 00:00:00 EST 2013 · Journal of the American Chemical Society

DOI:https://doi.org/10.1021/ja4081056· OSTI ID:1118758

Cao, Bingfei ^[1]; Veith, Gabriel M ^[1]; Neuefeind, Joerg C ^[1]; Adzic, Radoslav R. ^[2]; Khalifah, P. ^[3]

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1. ORNL
2. Brookhaven National Laboratory (BNL)
3. Stony Brook University (SUNY)

A two-step solid-state reaction for preparing cobalt molybdenum nitride with a nanoscale morphology has been used to produce a highly active and stable electrocatalyst for the hydrogen evolution reaction (HER) under acidic conditions that achieves an iRcorrected current density of 10 mA cm 2 at 0.20 V vs RHE at low catalyst loadings of 0.24 mg/cm2 in rotating disk experiments under a H2 atmosphere. Neutron powder diffraction and pair distribution function (PDF) studies have been used to overcome the insensitivity of X-ray diffraction data to different transition-metal nitride structural polytypes and show that this cobalt molybdenum nitride crystallizes in space group P63/mmc with lattice parameters of a = 2.85176(2) and c = 10.9862(3) and a formula of Co0.6Mo1.4N2. This space group results from the four-layered stacking sequence of a mixed close-packed structure with alternating layers of transition metals in octahedral and trigonal prismatic coordination and is a structure type for which HER activity has not previously been reported. Based on the accurate bond distances obtained from time-of-flight neutron diffraction data, it is determined that the octahedral sites contain a mixture of divalent Co and trivalent Mo, while the trigonal prismatic sites contain Mo in a higher oxidation state. X-ray photoelectron spectroscopy (XPS) studies confirm that at the sample surface nitrogen is present and N H moieties are abundant.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1118758
• Journal Information: Journal of the American Chemical Society, Vol. 135, Issue 51; ISSN 0002--7863
• Country of Publication: United States
• Language: English