Abstract: Z-scheme heterojunction is an effective strategy in photocatalysis, when hetero-interfacial intimate contact is the center of high-performance Z-scheme heterojunction structure. Here, x-MoS₂ [x = plate (p), flower (f), and solid sphere (s)] with extensive optical absorption and high conductivity and stable UiO-66-NH₂(y) (y = 100, 300, and 500 nm) with rich Lewis's acid sites were integrated to a series of x-MoS₂@UiO-66-NH₂(y) Z-scheme heterojunctions, which were fully characterized and used for photocatalytic reduction of CO₂ (pCO₂RR) into CH₄ and CO. In response to the difficult modification of MoS₂ and loose contact of composite bulk materials, the micro-geometric configurations on the size of UiO-66-NH₂ and the morphology of MoS₂ were optimized to achieve an intimate contact. The Z-scheme heterojunction f-MoS₂@UiO-66-NH₂ (100 nm) with perfectly matched micro-geometric configuration exhibited an excellent electron consumption rate (R_ele) of 263.78 μmol g^-1 h^-1 and a high CH₄ yield of 27.18 μmol g^-1 h^-1 with a selectivity of 82.44%, being far superior to most MoS₂- and MOFs-based heterojunctions. Comprehensive investigations with extensive photoelectric characterizations, control experiments, and density functional theory (DFT) calculations demonstrate that the excellent photocatalytic performance of f-MoS₂@UiO-66-NH₂ (100 nm) could be attributed to that (i) the low size of UiO-66-NH₂ strengthens mutual alignment and increases outer surface to maximize heterointerface contact with MoS₂, accelerating the interfacial charge transfer; (ii) the hierarchical structure of f-MoS₂ with optimal basal plane curvature greatly reduces contact barriers to present a high charge throughput with a charge excitation rate of 1.967 mV, smooth initiating the 8-electron CO₂ methanation. Additionally, the durability of f-MoS₂@UiO-66-NH₂ (100 nm) was also investigated.

Key words: Heterojunction, Photocatalysis, Carbon dioxide reduction, Metal-organic frameworks