Twin S-Scheme Heterojunction ZnO/UiO-66-NH2@ZnIn2S4 Rhombic Octahedra for Efficient Photocatalytic H2 Evolution

Abstract

Amid increasing fossil energy scarcity, a key solution is using solar energy to split water into hydrogen (H2). However, single photocatalysts face limitations of low solar utilization rate and rapid carrier recombination, so constructing novel composite photocatalysts is a promising solution. Here, a novel ZnO/UiO-66-NH2@ZnIn2S4 (ZUN@ZIS) composite catalyst with twin S-scheme heterojunction is constructed for the first time, in which ZnIn2S4 (ZIS) nanosheets are grown in situ on the surface of ZnO/UiO-66-NH2 (ZUN) rhombic octahedra. Under the irradiation of visible light and without the help of any co-catalyst, the H2 evolution rate of the prepared ZUN@ZIS-20 is 5.05 mmol g−1 h−1, which is 3.7, 2.1 and 46 times higher than that of ZIS, UiO-66-NH2/ZIS (UN/ZIS) and ZUN, respectively. Moreover, the synergistic effect of the resulting ZUN@ZIS twin S-scheme heterojunction facilitates the provision of efficient channels for carrier/mass transfer and ensures structural stability. Various experimental characterizations and theoretical calculations confirm that the twin S-scheme heterojunction constructed by ZUN and ZIS can facilitate the easy separation and transfer of photogenerated carriers. This study has developed a new idea for the efficient H2 evolution of multi-heterojunction photocatalysts, and provided a valuable reference for the development of H2 energy in photocatalysis technology.