Phosphorus doped nickel selenide for full device water splitting

The lack of high active and stable electrocatalysts has impeded the development of electrochemical water splitting device, which is promising technique for renewable energy conversion system. Here, we report a one-step protocol to synthesize P doped NiSe₂ (P-NiSe₂) by selenylation process derived from nickel foam with assistant of NaH₂PO₂ and Se powder. The P-NiSe₂ could be directly used as working electrode and shows the superior electrochemical activity, offering current density of 10 mA cm^-2 with overpotential of 270 mV for OER and 71 mV for HER. The enhanced electrochemical activity can be ascribed to the P atom doping. The P atom doping leads to the high valence state of Ni active sites, which have high catalytic ability towards OER. Moreover, the P doping makes the d-band center of Ni atoms in P-NiSe₂ move close to Fermi level, facilitating the HER kinetics with respect to proton adsorption and hydrogen desorption. When employed P-NiSe₂ as both anodic and cathodic electrode in alkaline water electrolyzer, a current density of 10 mA cm^-2 can be achieved at 1.58 V. Our work highlights the importance of P doping in determining the surface electron configuration for full device water splitting and the facile synthesis protocol would be promising for realistic applications.