Establishing Multiple-Order Built-in Electric Fields Within Heterojunctions to Achieve Photocarrier Spatial Separation.

Hybridizing two hetero-components to construct a built-in electric field (BIEF) at the interface represents a significant strategy for facilitating charge separation in carbon dioxide (CO 2 )-photoreduction. However, the unidirectional nature of BIEFs formed by various low-dimensional materials poses challenges in adequately segregating the photogenerated carriers produced in bulk. In this study, leveraging zinc oxide (ZnO) nanodisks, we employed a sulfurization reaction to fabricate Z-scheme ZnO/zinc sulfide (ZnS) heterojunctions featuring a multiple-order BIEF. These heterojunctions revealed distinctive interfacial structures characterized by two semi-coherent phase boundaries. The cathodoluminescence two-dimensional maps and density functional theory calculation results demonstrated that the direction of the multiple-order BIEF spanned from ZnS to ZnO. This directional alignment significantly fosters the spatial separation of photogenerated holes within ZnS nanoparticles and enhances CO 2 -to-carbon monoxide photoreduction performance (3811.7 εmol h -1  g -1 ). Our findings present a novel pathway for structurally designing BIEFs within heterojunctions, while providing fresh insights into the migratory behavior of photogenerated carriers across interfaces. This article is protected by copyright. All rights reserved.