Catalysts with excellent photocatalytic and electrocatalytic properties were highly desirable for improving hydrogen evolution reaction (HER) to produce green-H 2. Herein, a series of La-Ni-P samples were prepared from one-pot hydrothermal system and investigated for HER. The samples were identified in (LaPO 4) m /Ni 2 P nanocomposite structure with adjustable molar ratio m in 0.14–0.58 by ICP-OES, XRD, XPS and HRTEM characterization techniques. In dye (EY)-sensitized photocatalytic system, 9-fold enhancement in H 2 evolution rate was achieved on (LaPO 4) 0.22 /Ni 2 P in contrast to Ni 2 P (5450 versus 625 µmol h−1 g−1), and the obvious improvement in separation and transfer efficiency of photo-induced charge was demonstrated to be responsible for the superior HER performance on LaPO 4 /Ni 2 P interface. Electrocatalytic measurements disclosed that the overpotential for the reduction step to produce H 2 involved in HER would reduce from 312 mV on Ni 2 P to 191 mV on (LaPO 4) 0.22 /Ni 2 P with obviously lowered Tafel slope, the feature was supported by the observation that charge-transfer resistance (EIS analysis) on the sample (116 Ω) was much lower than that on Ni 2 P (331 Ω). These results clarified that LaPO 4 could act as an attractive component to improve HER performance of Ni-phosphide-based catalysts, the favorable and compatible photocatalysis and electrocatalysis features manifested by LaPO 4 /Ni 2 P interface gifted phosphate/phosphide composites the potential as promising catalysts for clean production of H 2. [Display omitted] • Better separation-transfer efficiency of photo-induced charge was achieved by attaching LaPO 4 on Ni 2 P. • Electrochemical barriers for reductive production of H 2 were greatly lowered on LaPO 4 /Ni 2 P interface. • 9-fold enhancement in H 2 -yield rate of photocatalytic HER occurred on LaPO 4 /Ni 2 P compared with Ni 2 P. [ABSTRACT FROM AUTHOR]