Abstract
Exploring high-efficient catalysts to reduce the voltage of the electrolytic cell is pivotal for large-scale hydrogen production, and using other electrochemical reactions to replace inert oxygen evolution reaction (OER) is also a feasible way. In this paper, a series of Ni[sbnd]Co precursors supported by carbon cloth (CC) were prepared by hydrothermal method and subsequently treated with phosphating and oxidation, respectively. The phosphating products and oxidation products were used for hydrogen evolution reaction (HER) and urea oxidation reaction (UOR), respectively. The materials morphology and electron configuration were also controlled by adjusting relative Ni[sbnd]Co content in the precursors. Furthermore, the effects of different Ni-Co ratios on electrocatalytic activity under the same crystal structure were discussed in detail. Benefited from the optimum electron structure and maximum active sites, Ni2Co1-P/CC displayed the best HER catalytic performance, with an overpotential of 79 mV to reach 10 mA cm?2. On account of the comparatively low theoretical oxidation voltage of urea, NixCo3?x-O/CCs displayed a much lower working potential in urea-containing electrolyte than the urea-free electrolyte. Thereinto, Ni1.5Co1.5-O/CC showed the best UOR catalytic performance, with a potential of 1.362 V at η10 in 1.0 M KOH and 0.33 M urea. With the combination of the above catalysts, it needed only 1.47 V to drive the current density of 10 mA cm?2 in the electrolytic cell for hydrogen production via UOR.
NSTL
Elsevier