Stepwise Coordination Engineering of Pt₁/Au₂₅ Dual Catalytic Sites with Enhanced Electrochemical Activity and Stability

Dual-site catalysts hold significant promise for accelerating complex electrochemical reactions, but a major challenge remains in balancing high loading with precise dual-site architecture to achieve optimal activity, stability, and specificity simultaneously. Herein, a strategy of stepwise targeted coordination engineering is introduced to co-anchor Pt single atoms (Pt₁, 1.41 wt.%) and Au₂₅(SG)₁₈ nanoclusters (Au₂₅, 18.92 wt.%) with high loadings on graphitic carbon nitride (g-C₃N₄). This approach ensures that Pt₁ and Au₂₅ occupy distinct surface sites on the g-C₃N₄ substrate, providing excellent stability and unprecedented electrochemical activity. In the catalysis of As(III), a sensitivity of 8.32 µA ppb⁻¹ is achieved, more than double the previously reported values under neutral conditions. The enhanced detection limit (0.2 ppb) is crucial for monitoring water quality and protecting public health from arsenic contamination, a significant environmental and health risk. Furthermore, the formation of Pt─As and As─S bonds facilitates the easier breakage of As─O bonds, thereby lowering the reaction barrier energy of the rate-determining step and significantly enhancing arsenious acid catalysis efficiency. These results not only offer an intriguing strategy for constructing highly efficient heterogeneous dual-site catalysts but also reveal the atomic-scale catalytic mechanisms that drive enhanced catalytic efficiency.