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

Abstract 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 (Pt 1 , 1.41 wt.%) and Au 25 (SG) 18 nanoclusters (Au 25 , 18.92 wt.%) with high loadings on graphitic carbon nitride (g‐C 3 N 4 ). This approach ensures that Pt 1 and Au 25 occupy distinct surface sites on the g‐C 3 N 4 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.