Electrosynthesis of hydrogen peroxide (H₂O₂), as a sustainable alternative to the anthraquinone oxidation method, provides the feasibility of directly generating H₂O₂. Here, we report Cu-doped TiO₂ as an efficient electrocatalyst which exhibits the excellent two-electron oxygen reduction reaction (2e⁻ ORR) performance with respect to the pristine TiO₂. The Cu doping results in the distortion of TiO₂ lattice and further forms a large number of oxygen vacancies and Ti³⁺. Such Cu-doped TiO₂ exhibits a positive onset potential about 0.79 V and high H₂O₂ selectivity about 91.2%. Moreover, it also shows a larger H₂O₂ yield and good stability. Density functional theory (DFT) calculations reveal that Cu dopant not only improves the electrical conductivity of pristine TiO₂ but reduces the *OOH adsorption energy of active sites, which is beneficial to promote subsequently 2e⁻ ORR process.

NH₃ is an essential feedstock for fertilizer synthesis. Industry-scale NH₃ synthesis mostly relies on the Haber–Bosch method, however, which suffers from massive CO₂ emission and high energy consumption. Electrocatalytic NO₃^– reduction is an attractive substitute to the Haber–Bosch method for synthesizing NH₃ under mild conditions. As this reaction will produce a variety of products, it highly desires efficient and selective electrocatalyst for NH₃ generation. Here, we report in situ grown Fe₃O₄ particle on stainless steel (Fe₃O₄/SS) as a high-efficiency electrocatalyst for NO₃^– reduction to NH₃. In 0.1 M NaOH with 0.1 M NaNO₃, such Fe₃O₄/SS reaches a remarkable Faradaic efficiency of 91.5% and a high NH₃ yield of 10,145 μg·h^–1·cm^–2 at –0.5 V vs. reversible hydrogen electrode (RHE). Furthermore, it owns robust structural and electrochemical stability. This work provides useful guidelines to expand the scope of metallic oxide electrocatalysts for NH₃ synthesis. The catalytic mechanism is uncovered and discussed further by theoretical calculations.