Enhanced Solar Fuel H2 Generation over g-C3N4 Nanosheet Photocatalysts by the Synergetic Effect of Noble Metal-Free Co2P Cocatalyst and the Environmental Phosphorylation Strategy

Highly active and durable earth-abundant cocatalysts and photocatalysts are under increasing demand in developing practical hydrogen-evolution reaction (HER) systems. Especially, exploiting noble-metal-free Pt-like HER cocatalysts still remains a significant challenge. In this study, the synergistic effect of metal–organic framework (MOF) derived earth-abundant Co 2 P cocatalysts and the robust bioinspired environmental phosphorylation strategy in boosting photocatalyic H 2 generation over the graphitic carbon nitride (g-C 3 N 4 ) nanosheets was thoroughly investigated and revealed. The maximum H 2 -evolution rate of the ternary g-C 3 N 4 -Co 2 P-K 2 HPO 4 photocatalytic systems could reach 27.81 μmol h –1, which was approximately 556 times higher than that of pure g-C 3 N 4 nanosheets. The loaded earth-abundant Co 2 P nanoparticles with a good electrical conductivity could not only improve visible-light absorption and decrease the recombination of the electron–hole pairs, but also mainly serve as an efficient cocatalyst to lower the H 2 -evolution overpotentials. Furthermore, K 2 HPO 4 could generate an additional H 2 -evolution pathway through proton-reduction cycle and enhance the oxidation ability of TEOA by effectively consuming the holes, thus significantly boosting photocatalytic hydrogen evolution of the binary g-C 3 N 4 -Co 2 P heterojunctions. It could be anticipated that this work will open a new pathway to rationally fabricate a noble metal-free, low-cost and high-activity metal phosphide cocatalyst for efficient photocatalytic hydrogen evolution over g-C 3 N 4 nanosheet photocatalysts under visible-light illumination.