Photoelectrochemical water splitting improved by a cucurbit[7]uril-induced ternary heterojunction

A promising method for producing hydrogen from solar energy and converting it into chemical fuels is photoelectrochemical (PEC) water splitting. In this paper, a novel photoanode is prepared by hydrothermal growing of nanorod CdS/g-C 3 N 4 /Q[7] heterojunction on FTO substrate for photoelectrochemical water splitting to produce hydrogen. In this method, Q[7]-doped g-C 3 N 4 is tightly combined with CdS composite and substrate, which significantly improves the separation and migration of photogenerated carriers in g-C 3 N 4 /Q[7] and CdS, and effectively reduces the internal resistance of the photoanode. Compared with the free CdS NRs, the PEC performance of the heterojunction CdS/g-C 3 N 4 /Q[7]-10 is significantly enhanced with the improved photocurrent density of 1049.7 μA/cm 2 under AM 1.5 G (100 mW/cm 2 ) simulated sunlight, which is 3.6 times that of pristine CdS and 2.6 times that of FTO-CdS/g-C 3 N 4 under the same conditions. The external bias photocurrent conversion efficiency and photohydrogen conversion efficiency of CdS/g-C 3 N 4 /Q[7]-10 photoanode at 0.7 V (relative to RHE) are measured to be both 0.31 %, as 3.1 times high as that of the original CdS NRs (0.10 %), and 2.07 times high as that of FTO-CdS/g-C 3 N 4 (0.15 %). The generation of heterostructure with interfacial interaction reduces the recombination of photogenerated electron-hole pairs, to enhance the charge transfer of water oxidation kinetics, allowing electrons to quickly transfer through the external circuit to the counter electrode for H + reduction to produce H 2 . A schematic diagram of the photoelectrochemical water splitting hydrogen evolution process with the heterojunction CdS/g-C 3 N 4 /Q[7]-10 is systematically proposed.