A new and highly efficient co-catalyst Zn-Ni5P4 for photocatalytic H2 evolution with the reduced capacitance via Zn doping

Non-noble metal co-catalysts for hydrogen production have capacitance characterization, which can store photo-excited electrons from semiconductor and show capacitance catalysis. However, the overlarge capacitance of co-catalysts constrains prompt release of electrons. Here, we reported a new and highly efficient co-catalyst Zn-Ni5P4 via evenly doping Zn in Ni5P4. Loading Zn-Ni5P4 on CdS, the photocatalyst Zn-Ni5P4/CdS shows an ultrahigh activity of 8969 μmol/g/h, which is 2.4 times of Ni5P4/CdS (3668 μmol/g/h). More interestingly, by the Pt loading on the surface of Ni5P4, the (Pt/Ni5P4)/CdS shows only 1.3 times of Ni5P4/CdS. Zn doping in Ni5P4 reduces the capacitance by 140 mF/g and electrochemical impedance, which benefits the release of photo-excited electrons. Moreover, the reduced overpotential and the increased specific surface area also account for the enhanced co-catalytic performance of Zn-Ni5P4. This paper presents an effective and low-cost method to inhibit negative effect of capacitance catalysis of non noble co-catalysts.