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Oxygen involved reactions, including oxygen reduction (ORR) and oxygen evolution reactions (OERs), play a key role in electrochemical energy devices, such as fuel cells and metal–air batteries. Recent theoretical calculations and experimental investigations reveal that the energy loss in ORR/OER is closely related to the triplet O2 generation/conversion step. However, the spin‐related phenomena have long been neglected in understanding of the ORR/OER mechanism. This review highlights recent advances in understanding and application of the spin‐related effect in oxygen electrocatalysis. It is demonstrated that the exchange interaction in magnetic catalysts can build a spin‐selective channel to filter the electron spins with appropriate orientation in the O2 generation/conversion step during ORR/OER. It is believed that the introduction of spin effect can establish a more comprehensive understanding of oxygen electrocatalysis and assist designing more reactive oxygen electrocatalysts.

Powered by inexhaustible solar energy, photoelectrochemical (PEC) hydrogen/ammonia production and reduction of carbon dioxide to high added-value chemicals in eco-friendly and mild conditions provide a highly attractive solution to carbon neutrality. Recently, substantial advances have been achieved in PEC systems by improving light absorption and charge separation/transfer in PEC devices. However, less attention is given to the atomic design of photoelectrocatalysts to facilitate the final catalytic reactions occurring at photoelectrode surface, which largely limits the overall photo-to-energy conversion of PEC system. Fundamental catalytic mechanisms and recent progress in atomic design of PEC materials are comprehensively reviewed by engineering of defect, dopant, facet, strain, and single atom to enhance the activity and selectivity. Finally, the emerging challenges and research directions in design of PEC systems for future photo-to-energy conversions are proposed.

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