Recent advances in bifunctional HER/OER TM@POM electrocatalysts for sustainable hydrogen production via water electrolysis

The development of electrocatalysts that can effectively promote the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is essential to the shift to sustainable hydrogen production. However, because of the frequently incompatible thermodynamic and electronic requirements of these two half-reactions, designing truly bifunctional catalysts continues to be a significant challenge. Based on important descriptors like the overpotential of the OER and the free energy of hydrogen adsorption (ΔG_H*), this review compares monoatomic transition metal electrocatalysts supported on polyoxometalates (TM@POM). Only a few systems, most notably Mn@PoT, provide a favorable bifunctional compromise, according to the HER–OER cross-analysis, whereas Sc@PoNb and Ru@PMA seem like promising but flawed candidates. Even though they are only partially specialized, the other catalysts under study provide pertinent platforms for focused electronic and structural property optimization to increase their bifunctionality. Therefore, the synthesized results offer a solid conceptual framework to direct the future development of bifunctional catalysts that combine durability, stability, and activity for global water electrolysis.