Cobalt based nanostructured alloys: Versatile high performance robust hydrogen evolution reaction electro-catalysts for electrolytic and photo-electrochemical water splitting

Engineering reduced noble metal containing electro-catalysts exhibiting superior electro-chemical performance is important for efficient and economic production of hydrogen from electrolytic and photoelectrochemical (PEC) water splitting reactions. In this study, nanostructured Co-Ir solid solution alloys, Co1-x(Ir-x) (x = 0.2, 0.3, 0.4) have been studied as electro-catalysts for hydrogen evolution reaction (HER). Co1-x(Irx) (x = 0.3, 0.4) exhibit similar onset over-potential to Pt/C and lower over-potential required for Co1-x(Ir-x) (x = 0.3, 0.4) than Pt/C in acidic, neutral as well as basic media, suggesting excellent electrochemical activity of Co-Ir alloys, further studied using theoretical first principles density functional theory calculations. Co1-x(Ir-x) exhibit excellent electrochemical stability in acidic media similar to that of Pt/C. The applied bias photon-to-current efficiency obtained using Co1-x(Ir-x) (x = 0.3, 0.4) electro-catalysts and (Sn0.95Nb0.05)O-2:N-600 NTs as photoanode in H-type cell is similar to 5.74% and similar to 7.92%, respectively which is similar to 40% and similar to 93% higher than Pt/C (similar to 4.1%) indicating considerable promise of the system. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.