• Heilmann, M.; Prinz, C.; Bienert, R.; Wendt, R.; Kunkel, B.; Radnik, J.; Hoell, A.; Wohlrab, S.; Guilherme Buzanich, A.; Emmerling, F.: Size-Tunable Ni-Cu Core-Shell Nanoparticles - Structure, Composition, and Catalytic Activity for the Reverse Water-Gas Shift Reaction. Advanced Engineering Materials 24 (2022), p. 2101308/1-13

10.1002/adem.202101308
Open Access Version

Abstract:
A facile and efficient methodology is described for the solvothermal synthesis of size-tunable, stable, and uniform NiCu core–shell nanoparticles (NPs) for application in catalysis. The diameter of the NPs is tuned in a range from 6 nm to 30 nm and to adjust the Ni:Cu ratio from 30:1 to 1:1. Furthermore, the influence of different reaction parameters on the final NPs is studied. The NPs are structurally characterized by a method combination of transmission electron microscopy, anomalous small-angle X-ray scattering, X-ray absorption fine structure, and X-ray photoelectron spectroscopy. Using these analytical methods, it is possible to elucidate a core–shell–shell structure of all particles and their chemical composition. In all cases, a depletion from the core to the shell is observed, with the core consisting of NiCu alloy, surrounded by an inner Ni-rich shell and an outer NiO shell. The SiO2-supported NiCu core–shell NPs show pronounced selectivity of>99% for CO in the catalytic reduction of CO2 to CO using hydrogen as reactant (reverse water–gas shift reaction) independent of size and Ni:Cu ratio.