The embedded CuInS2 into hollow-concave carbon nitride for photocatalytic H2O splitting into H2 with S-scheme principle

Abstract

It is still a great challenge to effectively optimize the electronic structure of photocatalysts for the sustainable and efficient conversion of solar energy to H2 energy. To resolve this issue, we report on the optimization of the electronic structure of hollow-concave carbon nitride (C3N4) by deviating the sp2-hybridized structure of its tri-s-triazine component from the two-dimensional plane. The embedded CuInS2 into C3N4 (CuInS2@C3N4) demonstrates an increased light-capturing capability and the promoted directional transfer of the charge carrier. Research results reveal that the hollow structure with an apparent potential difference between the concave and convex C3N4 drives the directional transfer of the photoinduced electrons from the Cu 2p orbital of CuInS2 to the N 1s orbital of C3N4 with the S-scheme principle. The H2 evolution efficiency over CuInS2@C3N4 is up to 373 µmol·h−1 g−1 under visible irradiation, which is 1.57 and 1.35 times higher than those over the bulk g-C3N4 with 1 wt% Pt (238 µmol·h−1 g−1) and g-C3N4 with 3 wt% Pd (276 µmol·h−1 g−1), respectively. This suggests that the apparent potential difference of the hollow C3N4 results in an efficient reaction between the photogenerated electrons and H2O. This work supplies a new strategy for enhancing the sustainable solar conversion performance of carbon nitride, which can also be suitable for other semiconductors.