Mn2N0.86/Mn4N-derived MnOOH and Pt dual co-catalysts work in synergy to drive g-C3N4 to achieve photocatalytic overall water splitting

Polymer carbon nitride (g-C 3 N 4 ) demonstrates a thermodynamically favorable profile for photocatalytic overall water splitting. Nonetheless, the practical catalytic performance is limited by slow reaction kinetics, mainly because of the inadequate quantity of surface redox-active sites. It is evident that pristine g-C 3 N 4 shows minimal activity in the photocatalytic process of overall water splitting. Herein, we developed a strategy for achieving pure water splitting using photoexcited g-C 3 N 4 with MnOOH and Pt serving as redox cocatalysts. The innovation of this work is based on the deposition of Mn 2 N 0.86 /Mn 4 N onto g-C 3 N 4 as a precursor material. This precursor undergoes in-situ hydrolysis to form Mn(OH) 2 and in-situ photo-oxidation to generate MnOOH, which acts as an oxygen evolution cocatalyst by capturing photogenerated holes and facilitating the oxygen evolution reaction. Concurrently, H 2 PtCl 6 is employed as a precursor and undergoes in-situ photo-reduction to form Pt nanoparticles, which serve as a hydrogen evolution cocatalyst by capturing electrons and promoting the hydrogen evolution reaction. With the synergistic effect of these dual cocatalysts, efficient photocatalytic water splitting was achieved, yielding hydrogen (11.64 μmol h −1 ) and oxygen (5.47 μmol h −1 ) in a nearly 2:1 stoichiometric ratio under light irradiation.