Recent progress in synergistic electrocatalysis for generation of valuable products based on water cycle

Given the grim situation of global warming and energy crisis, replacing traditional energy conversions based on carbon cycle with water cycle is a sustainable development trend. The synergistic electrocatalysis for value-added chemical production through oxygen species (Oads: OH*, O*, and OOH*) and the active hydrogen species (Hads) derived from water splitting powered by "green" electricity from renewable energy resource (wind, solar, etc.) is a promising manner, because of its reduced energy consumption and emission and high Faradaic efficiency. The study and summarization of catalytic mechanism of synergistic electrocatalysis are particularly significant, but are rarely involved. In this review, recent progress of various synergistic electrocatalysis systems for generating valuable products based on water cycle is systematically summarized. Importantly, the catalytic mechanism of synergistic electrocatalysis and the positive effect of Oads and Hads species produced by water splitting during the synergistic electrocatalytsis are detailedly elucidated. Furthermore, the regulation of water-derived Oads and Hads species for achieving efficient matchability of synergistic electrocatalysis is emphatically discussed. Finally, we propose the limitations and future goals of this synergistic system based on water cycle. This review is guidance for design of synergistic electrocatalysis architectures for producing valuable substances based on water cycle.