FeNiP three-dimensional oriented nanosheet array bifunctional catalysts with better full water splitting performance than the full noble metal catalysts.

The 3D (three-dimensional) oriented nanosheet array FeNiP electrocatalyst grown on carbon cloth (FeNiP/CC) is explored in this work. This unique 3D oriented nanosheet array structure can expose more catalytic active sites, promote the penetration of electrolyte solution on the catalyst surface, and facilitate the transfer of ions, thus speeding up the kinetic process of Hydrogen evolution reaction (HER) and Oxygen evolution reaction (OER). At the current densities of 10 mA/cm in 1 M KOH solution, the HER overpotential (71 mV) of the FeNiP/CC self-supporting electrode is very close to that of noble metal HER catalyst of 20% Pt/C (54 mV), and its OER overpotential (210 mV) is 34% lower than that of the precious metal OER catalyst of RuO (318 mV), demonstrating the excellent electrocatalytic performance of the FeNiP/CC catalyst. Moreover, the cell voltage for full water splitting (at 10 mA/cm current densities) of the FeNiP/CC bifunctional electrode cell is 1.52 V, which is 3.8% lower than that of the full noble-metal electrode reference cell (RuO || Pt/C, 1.58 V), suggesting that this FeNiP/CC bifunctional catalyst is likely to replace precious metals to reduce the costs in full water splitting application. According to density functional theory (DFT) calculation results, the introduction of iron atom can change the electronic structure of the NiP, so it can reduce the adsorption energy of hydrogen and oxygen, and facilitate the adsorption and desorption of hydrogen and oxygen on the surface of the catalyst, improving its performance of HER and OER.