Lattice-matched MnxCd1-xS@MnS heterojunction photocatalysts: High-intensity built-in electric field boosts photocatalytic U(VI) reduction

The lattice-matched heterointerface can improve the separation and directional transportation of photocarriers. Nevertheless, the randomness of interface orientation often leads to lattice mismatch and high resistance, thereby limiting the efficiency of interface charge transfer within the built-in electric field. Herein, a lattice-matched Mn x Cd 1-x S@MnS (MCS@MS) heterostructure has been successfully constructed through a one-step hydrothermal method for the effective photocatalytic reduction of U(VI). Experimental results and Density Functional Theory (DFT) calculations indicate that, compared to heterojunction prepared by a two-step hydrothermal method , the lattice-matched heterojunction prepared by the one-step method exhibits higher charge separation efficiency and longer photogenerated carrier lifetime and can rapidly reduce U(VI) to U(IV) with a reduction rate of 86.81 % within one hour. Furthermore, in-situ Electron Spin Resonance (ESR) spectroscopy elucidates that the primary active species responsible for the photocatalytic reduction are superoxide radicals (•O 2 - ). The work presented in this paper provides a novel perspective for developing high-activity noble-metal-free photocatalysts for uranium reduction based on lattice-matching engineering. The effective photocatalytic reduction of U(VI) has been facilitated by the successful construction of a lattice-matched Mn x Cd 1-x S@MnS heterostructure , which was achieved through a one-step hydrothermal method . • The lattice-matched MCS@MS heterostructure has been successfully constructed through a one-step hydrothermal method . • The lattice-matched heterojunction exhibits exceptional charge-carrier transportation and carrier-oriented accumulation. • The heterojunction catalyst can rapidly reduce U(VI) to U(IV) within 1 h, achieving a reduction efficiency of 86.81 %. • This work provides a novel perspective for developing high-activity photocatalysts based on lattice-matching engineering.