Investigation of Activity of Sputtered Transition-Metal (TM)–C–N (TM = V, Cr, Mn, Co, Ni) Catalysts for Oxygen Reduction Reaction

Abstract

Variations with heat-treatment temperature of the structure and the electrocatalytic activity of sputtered transition-metal (TM)–C–N ( TM=V , Cr, Mn, Co, and Ni) films for the oxygen reduction reaction (ORR) in acid and alkaline electrolytes were studied. The films prepared were all originally amorphous. At a critical heat-treatment temperature ( Tc , different for each composition) substantial nitrogen release occurred and the films transformed to a heterogeneous N-containing carbon structure with either normalCr3normalC2 , Co, Ni, normalV8normalC7 , or normalMn7normalC3 , depending on the TM used. In acid electrolyte, heat-treated normalCrxnormalC1−x−ynormalNy , normalCoxnormalC1−x−ynormalNy , and normalNixnormalC1−x−ynormalNy films began to show oxygen reduction activity at Tc , while normalVxnormalC1−x−ynormalNy and normalMnxnormalC1−x−ynormalNy films showed little or no activity for ORR in acid electrolyte for all temperatures studied. However, all of the heat-treated TMxnormalC1−x−ynormalNy ( TM=V , Cr, Mn, Co, and Ni) films showed oxygen reduction activity in alkaline electrolyte even when heated to temperatures below Tc . Because all the TMxnormalC1−x−ynormalNy films heated above Tc contained N-containing carbon, the activity of heat-treated sputtered normalC1−xnormalNx and C films, as well as graphite powder, were studied for comparison. Their activities were much lower in acid electrolyte than those of the normalCrxnormalC1−x−ynormalNy , normalCoxnormalC1−x−ynormalNy , and normalNixnormalC1−x−ynormalNy films heat-treated at the same temperatures. normalC1−xnormalNx films, C films, and graphite powder all showed activity in alkaline electrolyte but were less active than some heated normalCoxnormalC1−x−ynormalNy and normalNixnormalC1−x−ynormalNy films. The choice of TM and the heat-treatment temperature played important roles in determining the activity of the sputtered TMxnormalC1−x−ynormalNy films for ORR in acid and alkaline electrolytes. The corrosion stability of the heat-treated TMxnormalC1−x−ynormalNy libraries was studied as well. Heat-treated normalCrxnormalC1−x−ynormalNy libraries showed good passivation against corrosion.

Progress in non-precious metal oxide-based cathode for polymer electrolyte fuel cells

“…Yang and co-workers have regularly investigated the applicability of transition metal carbonitrides as cathodes for PEFC [21,29,30]. Their investigations were derived from the research of transition metal complexes [31].…”

Impact of Loading in RRDE Experiments on Fe–N–C Catalysts: Two- or Four-Electron Oxygen Reduction?

“…[14][15][16] The initially amorphous and inactive films, prepared on GC disks, have shown, depending on their composition, activity for oxygen reduction when annealed between 700 and 800°C. Some of the better Fe-N-C compositions, as illustrated in Fig.…”

Electrochemical behaviour of oxygen reduction on polymer carbon electrodes in alkaline media

“…The maximum pyrolysis temperature of the electrodes preparation is 700°C. Cobalt/carbon electrodes for the oxygen reduction are well docu mented in the open literature [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44]. The activity of the prepared PC electrodes in comparison to that of a platinum (Pt) electrode is also illustrated.…”