Interface engineered Co₃O₄-BiVO₄ binary S-scheme heterostructure with improved topological features for enhanced...

In this study, urea assisted simple hydrothermal protocols were designed for fabrication of pristine BiVO₄ with dendritic structure and Co₃O₄ having sea urchin like morphology. The in situ integration of the semiconductors resulted in Co₃O₄-BiVO₄ (COxBVO) 1D-2D heterojunctions with a distinct nanorod-on-plate physiognomy. Structural investigations, XPS, ESR and O₂ TPD study revealed formation of an oxygen deficient p-n heterojunction with stabilization of monoclinic BiVO₄ and cubic Co₃O₄ phases. Rietveld refinement and Fourier analysis of XRD patterns revealed notable distortion and generation of microscopic strain in the BiVO₄ crystal structure due to oxygen vacancies creation and heterostructure formation. Investigation of optoelectronic properties of the p-n heterostructures revealed a significant improvement in visible light response, charge mobility and higher electrochemically active surface area than the pure components. The COxBVO displayed excellent activity towards photocatalytic H₂ production (4260 μmolg^-1h^-1) and N₂ reduction reaction (232.8 μmol g^-1h^-1) with reaction rates 5-7-fold greater than pure semiconductors. The apparent photon utilization efficiency of the optimal CO20BVO heterojunction was 27.2 and 1.8 % for H₂ evolution and N₂ reduction reaction, respectively. Based on detailed band architecture analysis, in situ XPS and radical trapping experiments, an S-scheme charge mobilization mechanism has been elucidated to explain the superior photocatalytic activity. This study illustrated the combined effect of topology, atomic defects and construction of 1D-2D p-n heterojunction for rapid conversion of atmospheric molecules to H₂ energy and valuable chemicals.