Electronic structure modulation and morphological engineering of trifunctional Ni x Co y P electrode for ultrastable overall water splitting at 1 A cm-2 and efficient biomass oxidation valorization

The development of transition metal electrocatalysts with excellent HER, OER and HMFOR activity can accelerate the achievement of "carbon peaking and carbon neutrality". Herein, we report a simple structure modulation and morphological strategy for constructing NixCoyP-3 nanoneedles array with superhydrophilic/ aerophobic surface. The small and well-dispersed nanoneedles can expose a larger electrochemical surface area. It has good mechanical stability, which can withstand the impact of violent bubbles at ampere-level current densities. NixCoyP-3 has a stronger H2O adsorption capacity than Ni2P, and can promote the adsorption and desorption of H* to facilitate the HER process. During the OER process, the formation of the NixCoyP-3/NixCoyOOH heterostructure is an important factor to stabilize oxygen evolution at ampere-level current densities. During the HMFOR process, NixCoyP-3 has a stronger HMF adsorption energy than Ni2P, and the generated FDCA can be desorbed from the NixCoyP-3 surface more easily. The overpotentials of the NixCoyP-3 are only 38.8 mV and 231.2 mV for HER and OER at 10 mA cm-2 in alkaline medium. When in the 1.0 M KOH + 50 mM HMF, only 1.37 V was required to reach a current density of 10 mA cm-2 of the NixCoyP-3 II NixCoyP-3 two-electrode system. NixCoyP-3 can drive 1000 mA cm-2 overall water splitting for 100 h of stable operation in 1 M KOH, validating its potential in industrial hydrogen production.