Photocatalytic and electrocatalytic CO₂ conversion: from fundamental principles to design of catalysts

Carbon dioxide (CO 2 ) is regarded as a major contributor to global warming and the climate crisis. To mitigate its negative impacts, a potential strategy is adopted, namely converting CO 2 into renewable fuels or valuable chemicals. Because of the sluggish thermodynamic and kinetic processes, catalysts (photocatalysts or electrocatalysts) are essential during CO 2 reduction. In this review, fundamental concepts, catalytic principles and reaction pathways related to photocatalysis and electrocatalysis for CO 2 reduction are provided, along with a survey of the progress in the rational design of new photocatalysts and electrocatalysts for CO 2 reduction. Discussions in the field are mainly focused on the design strategies of catalysts that have been introduced to increase visible light excitation, improve charge separation and enhance CO 2 adsorption of photocatalysts and alter electronic and geometric properties of electrocatalysts. Finally, recommendations and outlook for improving the selectivity of CO 2 reduction and in achieving efficient, stable and selective CO 2 photocatalysts or electrocatalysts are pointed out.