Boosting pH-universal hydrogen evolution of the In/Cu3P Mott-Schottky heterojunction electrocatalyst by constructing the ohmic contact and promoting water activation

Developing high-activity electrocatalysts compatible with pH-universal electrolytes is critical for efficient hydrogen production via water splitting. Herein, an In/Cu 3 P Mott-Schottky heterojunction electrocatalyst was fabricated through a facile electrodeposition method. The as-synthesized In/Cu 3 P exhibits exceptional hydrogen evolution reaction (HER) performance across acidic, neutral, and alkaline media, achieving low overpotentials of 36 mV, 68 mV, and 51 mV at a current density of 10 mA cm −2 , respectively. It also maintains robust stability for 400 h at 50 and 100 mA cm −2 in acidic electrolyte, outperforming most reported electrocatalysts. Interface electronic analysis and energy band structure characterization confirm the formation of strong ohmic contact between In and Cu 3 P, which effectively reduces interfacial charge transfer resistance. Interfacial electron transfer from In to Cu 3 P fine-tunes the d-band center and optimizes the hydrogen binding energy at the heterojunction interface. Additionally, the In/Cu 3 P Mott-Schottky structure promotes H 2 O activation and lowers the energy barrier in alkaline and neutral solutions. The intimate interface also inhibits copper dissociation from the Cu 3 P lattice, ensuring long-term stability in harsh electrolytes. This work establishes a theoretical foundation for designing pH-universal HER electrocatalysts via metal–semiconductor interfaces and provides a promising strategy for developing high-efficiency electrochemical catalysts.