Enhanced photocatalytic pure water splitting of porous g-C3N4/CdS composite by the bimetallic phosphide

Abstract

Here, a novel CoNiP nanoclusters-decorated photocatalyst consisted of porous g-C3N4 (PCN) and CdS were reported for the pure water splitting. Under visible light (λ ≥ 400 nm), the activities and durability for photocatalytic water splitting over the PCN-CdS composite can be importantly improved by CoNiP. And the photocatalytic H2-evolution rate could be maximized to 122.08 μmol g‐1 h‐1 for pure water-splitting through regulating the loading amount of CoNiP and the ratio of Co, Ni and P, which are all larger than those of PCN-CdS, PCN-CdS-Pt, PCN-CdS-Co2P and PCN-CdS-Ni2P. Comparing to the single metal phosphides (Co2P and Ni2P), the higher photocatalytic activities of PCN-CdS enhanced by the bimetallic phosphide (CoNiP) are on account of the extended light absorption, more exposed active sites, the regulated electronic structure, accelerated electrons transfer, the more negative Fermi energy and more trapped electrons in CoNiP. In addition, the PCN-CdS-CoNiP composite exhibits the high stability during the 3 cycling tests for 12 h, due to its stable structure resulted by the reinforced chemical connection between PCN and CoNiP in a form of P+-Pδ--Coδ+/Niδ+, in which the positive charge center (P+) originates from the replacement of C in PCN by P. This research indicates that the bimetallic phosphide could be a promising candidate of precious metals substitutes in photocatalyst system with higher activities.