Pd Single‐Atoms Doped Cu ₃ P Quantum Dots with Moderately Optimized H* Sorption Behaviors for Actualizing the Multifunctional “Formaldehyde‐Nitrate” Galvanic System

Nitrate and formaldehyde, which are substantial wastes in industrial and agricultural effluents, pose significant hazards to the human health and ecosystem. Current purification technologies remain great challenges due to the unsatisfactory energy-intensive, time-consuming and noticeably costly reasons. Herein, a bifunctional electrocatalysts of Pd single-atoms doped Cu₃P quantum dots (Pd-Cu₃P SA-QDs) are reported to moderately optimize the H* sorption behaviors for accelerating the kinetics of nitrate reduction (NO₃RR) and formaldehyde oxidation (FOR) reactions in a dual-directional way, thus realizing the high activity and selectivity for both cathodic ammonia (NH₃) synthesis and anodic H₂ production concurrently. Specifically, a very positive onset potential of +0.36 V (versus RHE) is recorded for NO₃RR with a high faradaic efficiency (FE) of 99 % for NH₃ at -0.3V (versus RHE), while the FOR can be initialized at a very low onset potential of -0.07 V (versus RHE) with > 90 % FE for formate and > 95 % FE for H₂ at 0.3 V (versus RHE). Notably, a self-powered galvanic system can be triggered by integrating the above two electrode-based reactions, thus exhibiting an open-circuit voltage of 0.892 V, a peak power density of 12.1 mW cm^-2, and capable of generating 8.8 KWh kg^-1 of electrical energy.