Scalable and Customizable Single-Atom Coatings for pH-Universal H₂O₂ Electrosynthesis

Achieving scalable fabrication of robust and uniform single-atom catalyst-based gas-diffusion electrodes (SAC-GDEs) remains challenging. Here, a universal one-step soot-deposition route was developed to convert various metal-containing paraffins into conformal single-atom catalyst (SAC) coatings on diverse electrodes (1D fibers, 2D plates, and 3D foams). The process provides multiscale control, from precursor-defined molecular coordination to micropore wettability and macroscopic geometry, to collectively engineer hierarchical coating films that couple intensified mass transfer and high intrinsic catalytic activity for efficient H₂O₂ electrosynthesis. As a device-level demonstration, Pd-SAC-GDE delivers pH-universal H₂O₂ production under an industrial-level current (500 mA cm^-2) for 100 h, achieving a record-high H₂O₂ yield of 16.9 mol g^-1 h^-1. A tip-enhanced mechanism was proposed based on constant-potential calculations. The results reveal that the curvature-enhanced localized electric field promotes O₂ polarization and activation at the Pd-O₃ sites, thereby facilitating both ^*OOH generation and adsorption and ultimately leading to highly selective H₂O₂ production. This facile, broadly applicable fabrication strategy significantly advances the scalable manufacture of SAC-coated GDEs for environmental and sustainable catalysis.