Optimizing CO preferential oxidation pathways via active-site engineering: A case study on MgO nano-sheets supported ultrasmall PtNi alloys

Active-sites play a pivotal role in catalyzing reactions at surfaces, yet engineering these active sites still remains a significant challenge. In this work, hydroxylated MgO nanosheets supported ultrasmall PtNi alloys approximately 2.6(1) nm ( x Pt- y Ni/MgO hydr ) has been investigated via active-site engineering. Experimental results and DFT calculations reveal that electron transfers from Ni to Pt and from hydroxyl groups to Pt 5d-orbitals generate active sites NiPt-(OH) x . In the preferential CO oxidation (CO-PROX) reaction, these active sites on x Pt- y Ni/MgO hydr switch the bicarbonates reaction pathway depending on temperature range. Consequently, the optimal catalyst, 5%Pt-0.5%Ni/MgO hydr , achieves 100% CO conversion at 100 °C, demonstrating a broad temperature operation window (100–200 °C) and excellent durability. The active site engineering approach presented in this study can promote the discovery of more excellent catalysts with the optimal reaction route for various applications.