Effect of multi-interface electron transportation and molecule adsorption on hydrogen evolution reaction

The widespread industrial application of water electrolysis to hydrogen production is limited by its high cost, high energy consumption and low conversion efficiency. This work demonstrates the energy-efficient hydrogen production can be attained by the rational design of electrolyser with efficient electrocatalyst. Typically, the efficient CoP3-FeOOH-Ni2P-C3N4 (CoFeNiC) electrocatalyst is prepared by calcining the mixture of both ZIF-67 and NiFe-LDH, which exhibits a good electrolysis performance in an alkaline electrolyte. At 10 mA cm−2, the oxygen evolution reaction (OER) overpotential of CoFeNiC (146 mV) is lower than the previously reported results, and the Faraday efficiency (FE) reaches 94.8 %. In addition, density functional theory (DFT) calculations demonstrate that the large work function difference between FeOOH, Ni2P and C3N4 is beneficial to form stable hetero-interface, which significantly optimize the interface electronic structure and enhances the electron transfer from FeOOH, Ni2P to C3N4; and CoP3 has a strong molecule adsorption ability. Thereby CoFeNiC shows an enhaned water-splitting efficiency. Moreover, an asymmetric electrolyzer is constructed by using CoFeNiC as cathode and NiFe-LDH as anode. At 150 mA cm−2, the cell voltage of CoFeNiC//NiFe-LDH electrolyzer decreases by 11.67 %, compared with symmetric NiFe-LDH electrolyzer. The i-t test shows that the asymmetrical electrolyzer exhibits a good stability at a high current density.