Enhancement of CO2 adsorption performance and widening of adsorption temperature window by co-doping different valence state metals on the Li4SiO4 (010) surface

Lithium silicate (Li4SiO4) has good stability, high theoretical carbon dioxide (CO2) adsorption capacity, and low regeneration temperature. It has great potential in the field of CO2 adsorption. However, it is difficult to achieve the theoretical value in practical applications and a narrow temperature window for adsorption. Therefore, further research in this area is urgently needed. In this study, experimental and simulation methods were used to investigate the effects of single doping and co-doping with K, Na, Be, Ca, and Al metals on the adsorption performance and adsorption temperature window of Li4SiO4. Single doping with K, Na, or Al makes CO2 easier to be adsorbed on the Li4SiO4 (010) surface by increasing the charge transfer from the Li4SiO4 surface to CO2. Codoping with K and Al increases the adsorption energy of CO2 on the Li4SiO4 (010) surface, enhances hybrid peaks, and broadens the temperature range for CO2 adsorption on the Li4SiO4 surface. It exhibits stable cyclic adsorption performance under low CO2 (15% CO2, N2 balance) concentration, and more electron transfer facilitates the formation of carbonate species on the Li4SiO4 (010) surface at lower temperatures, thereby improving its CO2 adsorption performance.