Polyoxometalate-Based Compounds for Photo/electrocatalytic Applications.

Photo/electrocatalysis of water (H 2 O) splitting and CO 2 reduction reactions is known as the promising means to alleviate the energy crisis and excessive CO 2 emissions. For the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), CO 2 reduction reaction (CO 2 RR) involved, the development of effective photo/electrocatalysts is critical to reduce the activation energy and accelerate the sluggish dynamics. Polyoxometalate (POM)-based compounds with tunable compositions and diverse structures are emerging as unique photo/electrocatalysts for these reactions as they offer unparalleled advantages such as outstanding solution and redox stability, quasi-semiconductor behaviour, etc. This Minireview provides basic introduction related to photo/electrocatalytic HER, OER and CO 2 RR, followed by the classification of  well-defined POM-based compounds toward different catalytic reactions. Recent breakthroughs in engineering POM-based compounds as efficient photo/electrocatalysts are highlighted. Finally, the advantages, challenges, strategies and outlooks of POM-based compounds on improving photo/electrocatalytic performance are discussed.