Quaternary CZTS nanoparticle decorated CeO2 as a noble metal free p–n heterojunction photocatalyst for efficient hydrogen evolution

Abstract

Practical implementation of photocatalytic hydrogen production has been required for the invention of efficient visible light absorption and low cost photocatalyst materials. n-Type metal oxides can couple with p-type semiconductors to provide p–n heterojunctions. This is one of the possible strategies to simultaneously address the visible light absorption and charge separation issues. Hence, a noble metal free quaternary Cu₂ZnSnS₄ (CZTS) decorated CeO₂ p–n heterojunction photocatalyst has been designed and confirmed by HRTEM, Raman and XPS analysis. The growth of CZTS on the surface of CeO₂ has significantly enhanced the hydrogen production performance. The optimal amount of CZTS loaded on CeO₂ achieved the highest hydrogen production efficiency of 2930 μmol h⁻¹ g⁻¹ under visible light illumination, which is 59 times higher than that for bare CeO₂. It may be due to the fact that bare CeO₂ contributes to UV light absorption. Moreover CeO₂ coupled with CZTS has induced visible light absorption, separation and transmission of photoinduced charge carriers. However, the PL intensity of CZTS decorated CeO₂ is significantly lower than that of the bare CeO₂, which clearly demonstrates that the composite impedes the rapid recombination of electron–hole pairs.