Photocatalytic H₂O₂ production is limited by slow interfacial charge transfer and poorly controlled adsorption of oxygen intermediates, which reduce the selectivity of the two-electron oxygen reduction reaction. We prepared an oxygen-vacancy-rich In-TCPP@W₁₈O₄₉ heterointerface to investigate the role of π–d orbital coupling in oxygen reduction. Experiments and calculations show that oxygen vacancies enhance hybridization between the π states of In-TCPP and the W 5d states of W₁₈O₄₉. This interaction promotes interfacial charge redistribution and modifies the local electronic structure of surface W sites. The resulting electronic changes facilitate interfacial electron transfer and regulate the adsorption energies of *O₂ and *OOH intermediates, favoring a selective two-electron pathway for H₂O₂ formation. The optimized In-TCPP@W₁₈O₄₉ produces H₂O₂ at 1045 μmol g^-1 h^-1 in pure water under ambient air, 10.7 times higher than W₁₈O₄₉, with a solar-to-chemical conversion efficiency of 1.66 %. These findings indicate how oxygen-vacancy-enhanced π–d coupling may influence oxygen reduction and provide insights into designing selective solar-driven oxygen reduction photocatalysts.

The microstructure design of electrode material is a crucial point to optimize the supercapacitor’s electrochemical properties. In this work, a Bi-based nanocomposite with a three-layer structure (Bi–Bi₂O₃@carbon armour (CA)/carbon dots (CDs)) is synthesized and investigated. This material inherits high capacitance and high activity from bismuth-based materials, and the coated CA protects the structure from complete oxidization and improves surface hydrophilicity. Furthermore, CDs in CA can enhance the ion conduction efficiency between the catalyst, carbon membrane, and electrolyte. As a consequence, the specific capacitance of the electrode reaches 973 F·g⁻¹ under 1 A·g⁻¹, and the energy density achieves 32.5 Wh·kg⁻¹ with a power density of 266.9 W·kg⁻¹, with impressive electrochemical stability that Coulomb efficiency of the electrode remains about 100% after 5000 cycles. Furthermore, in-situ Fourier transformation infrared (FT-IR) analyzes the structure evolvement of the material during synthesis and finds that the annealing process of the material removes a great number of oxygen-containing groups of CA and CDs, generating oxygen vacancies, defects, and thus active sites, which enhance the capacitance of the material.