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

Abstract

Engineering reduced noble metal containing electro-catalysts exhibiting superior electrochemical 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(Irx) (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(Irx) (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(Irx) exhibit excellent electrochemical stability in acidic media similar to that of Pt/C. The applied bias photon-to-current efficiency obtained using Co1−x(Irx) (x = 0.3, 0.4) electro-catalysts and (Sn0.95Nb0.05)O2:N-600 NTs as photoanode in H-type cell is ∼5.74% and ∼7.92%, respectively which is ∼40% and ∼93% higher than Pt/C (∼4.1%) indicating considerable promise of the system.