Metal@hollow carbon sphere nanoreactors for sustainable biomass and CO2 valorization

Abstract

Metal@hollow carbon sphere nanoreactors (MHCSs) are gradually attracting attention owing to their well-defined active sites, confined void space and controllable mass transfer rates with adjustable chemical composition in the fields of photocatalysis, electrocatalysis, and thermal catalysis related to biomass and CO₂ valorization. In particular, the design of MHCSs with aspirational confined microenvironmental effects, where structure–composition–activity correlation could be selectively enhanced, diminished or eliminated, plays a crucial role in biomass and CO₂ catalytic upgradation. In this perspective, the confined targeted synthesis strategies of MHCSs including the post-synthetic, pre-synthetic and one-step in situ confinement strategy have been comprehensively reviewed, showing the strengths and challenges of each category in the target synthesis process. Afterward, a distinctive viewpoint on the confined microenvironmental effects of MHCSs, i.e., mass transfer effect, metal size effect, void confinement effect, spatial compartmentation effect, surface modification effect, is highlighted. Moreover, the potential applications of MHCSs materials for biomass and CO₂ conversion are investigated as well as the physical properties and surface composition from which they benefit from MHCSs. Finally, perspectives and challenges encountered in the development of MHCSs for broader biomass and CO₂ conversion are presented, with the sincere expectation of contributing to the development of efficient selective catalysts in the fields.