Carbon monoxide-mediated one-pot synthesis of sub-15-nm PdAuAg alloy nanocrystals with tunable compositions and their catalytic properties

Uniform PdAuAg alloy nanocrystals with tunable compositions are facilely prepared via a one-pot synthesis. The use of carbon monoxide as the effective agent is crucial to assist the reduction of multiple metallic precursors simultaneously, which is greenly released from in situ thermal decomposition of W(CO)6 in a capped glass vial. The resulting PdAuAg products are featured within the size range of 9.3~11.7 nm and quasi-spherical shape, and their elemental compositions can be readily tuned by varying the molar ratios of corresponding metallic precursors. Interestingly, when the reductant is varied from carbon monoxide to ascorbic acid, the resulting products showed Au@PdAg core-shell elemental distribution, indicating the necessary role of carbon monoxide in dominating the formation of PdAuAg nanocrystals with a fully alloy phase. Using the reduction of 4-nitrophenol as the model reaction, their catalytic properties are evaluated, where the Pd4.1Au3.3Ag2.6 nanocrystals showed the highest apparent rate constant. Results from DFT simulations prove that the 4-nitrophenol adsorption shows a facet and atomic ratio-dependent behavior. The current work provides a feasible strategy to create trimetallic nanocrystals with isotropic shapes and tunable compositions, which could be potentially extended to other metals/alloys. Graphical abstract ToC Entry