Targeted doping induces interfacial orientation for constructing surface-functionalized Schottky junctions to coordinate redox reactions in water electrolysis

Tuning the surface properties of catalysts is an effective method for accelerating water electrolysis. Herein, we propose a directional doping and interfacial coupling strategy to design two surface-functionalized Schottky junction catalysts for coordinating the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Directional doping with B/S atoms endows amphiphilic g-C3N4 with significant n-/p-type semiconductor properties. Further coupling with Fe3C modulates the energy band levels of B–C3N4 and S–C3N4, thus resulting in functionalized Schottky junction catalysts with specific surface-adsorption properties. The space-charge region generated by the dual modulation induces a local "OH−- and H+-enriched" environment, thus selectively promoting the kinetic behavior of the OER/HER. Impressively, the designed B–C3N4@Fe3C||S–C3N4@Fe3C pair requires only a low voltage of 1.52 ​V to achieve efficient water electrolysis at 10 ​mA ​cm−2. This work highlights the potential of functionalized Schottky junction catalysts for coordinating redox reactions in water electrolysis, thereby resolving the trade-off between catalytic activity and stability.