Matched micro-geometrical configuration leading to hetero-interfacial intimate contact of MoS2@UiO-66-NH2 Z-scheme heterojunction for efficient photocatalytic CO2 reduction

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 (Rele) 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.