Recent progress in ligand-centered homogeneous electrocatalysts for hydrogen evolution reaction

Abstract

Recent advances in metal and metal-free ligand-centred electrocatalytic H2 evolution have been reviewed.

Electrocatalytic H2 Evolution by the Co‐Mabiq Complex Requires Tempering of the Redox‐Active Ligand

“…The H 2 evolution pathways of, e. g., pincer, thiosemicarbazone, and thiolate complexes are known to involve the redox‐active scaffold. Proton relay sites and redox‐active ligands are proposed to significantly enhance the kinetics of H 2 formation and decrease the HER overpotentials of metal complexes . However, a redox non‐innocent coordination environment also may result in non‐productive pathways .…”

Molecular Electrocatalysts for the Hydrogen Evolution Reaction: Input from Quantum Chemistry

“…[49] Most current researchi sa ctually focused on developing electrocatalysts that feature metal-centered reactivity.N evertheless, it seems that redox-active catalysts promoting electroand photochemical ligand-centered hydrogen evolution, as well as metal-free organic compounds, are very promising leads to interesting discoveries and creative ideas in the design of innovative molecular catalysts. The correlation between theory and experiment is critical to test and validate the theoretical predictions, and drive the methodological developments toward experimentally accessible systems.…”

“…Important directions to be followed for the future design of HER catalysts were recently discussed by Zhang and co-workers. [49] Most current researchi sa ctually focused on developing electrocatalysts that feature metal-centered reactivity.N evertheless, it seems that redox-active catalysts promoting electroand photochemical ligand-centered hydrogen evolution, as well as metal-free organic compounds, are very promising leads to interesting discoveries and creative ideas in the design of innovative molecular catalysts.…”

“…[49] It is worth mentioning that it is possible for the metal to assist in the catalytic cycle, acting as ar edox site, but the protonation sites are away from it, which requires intramolecular ET acrosst he ligand.W ed iscussed above af ew examples involving bis-thiosemicarbazone. [49] It is worth mentioning that it is possible for the metal to assist in the catalytic cycle, acting as ar edox site, but the protonation sites are away from it, which requires intramolecular ET acrosst he ligand.W ed iscussed above af ew examples involving bis-thiosemicarbazone.…”

“…There are several examples of catalysts in which the ligand alone does all the work, and we refer the interested readert o as pecialized review by Zhang and co-workers. [49] It is worth mentioning that it is possible for the metal to assist in the catalytic cycle, acting as ar edox site, but the protonation sites are away from it, which requires intramolecular ET acrosst he ligand.W ed iscussed above af ew examples involving bis-thiosemicarbazone. Grapperhaus andc o-workersp erformeda study on aC u II complex with such al igand.…”