RESUMEN
Elucidating the synergistic catalytic mechanism between multiple active centers is of great significance for heterogeneous catalysis; however, finding the corresponding experimental evidence remains challenging owing to the complexity of catalyst structures and interface environment. Here we construct an asymmetric TeN2-CuN3 double-atomic site catalyst, which is analyzed via full-range synchrotron pair distribution function. In electrochemical CO2 reduction, the catalyst features a synergistic mechanism with the double-atomic site activating two key molecules: operando spectroscopy confirms that the Te center activates CO2, and the Cu center helps to dissociate H2O. The experimental and theoretical results reveal that the TeN2-CuN3 could cooperatively lower the energy barriers for the rate-determining step, promoting proton transfer kinetics. Therefore, the TeN2-CuN3 displays a broad potential range with high CO selectivity, improved kinetics and good stability. This work presents synthesis and characterization strategies for double-atomic site catalysts, and experimentally unveils the underpinning mechanism of synergistic catalysis.
RESUMEN
For heterogeneous catalysts, the active sites exposed on the surface have been investigated intensively, yet the effect of the subsurface-underlying atoms is much less scrutinized. Here, a surface-engineering strategy to dope Ru into the subsurface/surface of Co matrix is reported, which alters the electronic structure and lattice strain of the catalyst surface. Using hydrogen evolution (HER) as a model reaction, it is found that the subsurface doping Ru can optimize the hydrogen adsorption energy and improve the catalytic performance, with overpotentials of 28 and 45 mV at 10 mA cm-2 in alkaline and acidic media, respectively, and in particular, 28 mV in neutral electrolyte. The experimental results and theoretical calculations indicate that the subsurface/surface doping Ru improves the HER efficiency in terms of both thermodynamics and kinetics. The approach here stands as an effective strategy for catalyst design via subsurface engineering at the atomic level.