Orbital hybridization and adsorption modulating in Mo/P co-doped Ni3S2 enables superior urea-assisted water electrolysis at industrial current density

Rational designing a robust bifunctional electrocatalyst for urea-assisted water splitting (UWS) toward a carbon-neutral economy is imperative factor to address the energy-intensive challenges of sustainable hydrogen production at industrial current densities. In this study, a Mo/P co-doped Ni 3 S 2 one-dimensional nanoarray, decorated with two-dimensional nanosheets (MP-Ni 3 S 2 ), is synthesized using an in-situ growth method. The optimized MP-Ni 3 S 2 exhibits a significant advantage in the urea oxidation reaction (UOR), achieving much lower potentials (1.346 V at 100 mA cm −2 and 1.505 V at 1000 mA cm −2 in 1.0 M + 0.33 M urea) comparable to the oxygen evolution reaction (OER), which requires 302 mV and 445 mV at the same current densities. The MP-Ni 3 S 2 ||MP-Ni 3 S 2 electrolyzer reduces the cell voltage from 2.146 V for overall water splitting (OWS) to 1.856 V for UWS at 500 mA cm −2 , surpassing most reported catalysts. Theocratical calculations demonstrate that Mo and P doping in Ni 3 S 2 , through the hybridization of Mo/Ni 3d and N/O 2p orbitals, effectively accelerates UOR kinetics by lowering the energy barrier in dehydrogenation and N-N coupling processes, while P doping optimizes the Gibbs free energy of hydrogen adsorption (ΔG H* ) to enhance HER activity, thereby synergistically improving overall performance. These findings offer a viable strategy for the development of energy-saving hydrogen production.