Manganese doping regulated the built-in electric field of FeBTC for enhanced photoelectrocatalytic hydrolysis

MOF-based Mott Schottky heterojunction has been researched as a promising photoelectrocatalytic material for oxygen evolution reaction (OER), but activity is severely limited by built-in electric field (BIEF). In this study, trace Mn doping strategy is used to enhance the BIEF of FeBTC/NIF, and the energy level configuration is also adjusted. Prepared Mn-FeBTC/NIF has excellent photoelectric coupling catalytic capability, requiring 309 mV overpotential to excite 100 mA cm−2 under illumination and maintaining stability for up to 48 h under different light conditions. Catalytic excellence stems from the elevated BIEF, which means Mn accelerated charge transport, modulated the charge density around the active center, effectively improving the catalytic activity. Moreover, the addition of Mn can effectively improve the conduction band (CB) and valence band (VB), reduce the energy band gap, improve the light absorption capacity and enhance the photocatalytic performance. This work provides new ideas for increasing the BIEF of heterojunction materials. [Display omitted] •Mn-FeBTC is prepared on metal substrate to form Mott-Schottky heterojunction.•Mn doping strengthens the built-in electric field of FeBTC/NIF.•Mn doping regulates the energy level structure of FeBTC semiconductor.•Mn-FeBTC/NIF requires 309 mV at 100 mA cm−2 to catalyze OER under light.•Mn-FeBTC/NIF operates stably for at least 48 h at 200 mA cm−2 for OER.