Light assisted CO2 reduction with methane over SiO2 encapsulated Ni nanocatalysts for boosted activity and stability

Abstract

In this study, earth-abundant methane was adopted as the reductant in CO₂ photoreduction (CRM) for energy storage. Light was introduced into the thermally driven reaction system with the aim to improve the catalytic performance of catalysts at low temperatures. Ni-based nanocatalysts of different morphologies were first adopted in light assisted CRM and some interesting phenomena were observed. One is that, with light irradiation, boosted initial catalytic activities were observed over all the Ni nanocatalysts. Hot electrons resulted from Ni plasmonic property and interband transition facilitated reactant activation and participated in the initial activity enhancement. Another phenomenon is that improved stability could be observed over yolk–shell Ni@SiO₂-yolk and core–shell Ni@SiO₂-core catalysts with light irradiation. Characterization of the spent catalysts revealed that, over the encapsulation-structured catalysts, with light irradiation, the amounts of deposited graphitic carbon increased with the sacrifice of active carbon deposition, and the smaller amount of detrimental active carbon deposition was regarded to be responsible for the improved stability. To the best of our knowledge, this study for the first time reports that light irradiation could exert effects on carbon formation behavior; meanwhile, it offers an approach to improve the activity and stability of nanocatalysts in CO₂ photoreduction.