Ligands modification strategies for mononuclear water splitting catalysts

Abstract

Artificial photosynthesis (AP) has been proved to be a promising way of alleviating global climate change and energy crisis. Among various materials for AP, molecular complexes play an important role due to their favorable efficiency, stability, and activity. As a result of its importance, the topic has been extensively reviewed, however, most of them paid attention to the designs and preparations of complexes and their water splitting mechanisms. In fact, ligands design and preparation also play an important role in metal complexes’ properties and catalysis performance. In this review, we focus on the ligands that are suitable for designing mononuclear catalysts for water splitting, providing a coherent discussion at the strategic level because of the availability of various activity studies for the selected complexes. Two main designing strategies for ligands in molecular catalysts, substituents modification and backbone construction, are discussed in detail in terms of their potentials for water splitting catalysts.

Tuning primary and secondary coordination spheres of ruthenium complexes for the homogeneous water oxidation reaction: a perspective from catalytic activity and overpotential

“…For example, the electron-donating groups (EDGs) present in the ligand lower the onset potential and stabilize the reaction intermediates with a high oxidation state during the WOR. 25,39,53,59 In addition, the lower overpotential of molecular water oxidation catalysts (MWOCs) is often manifested by utilizing a ligand with strong donating power, 60–63 although this strategy may not disrupt the scaling relationship between TOF and η . 64,65…”

Insights into the supramolecular and molecular electrocatalytic properties of 1,2-bis(diphenylphosphine)ethane appended nickel(ii) 1,2-dithiosquarate for oxygen and hydrogen evolution reactions

“…14 The unusual redox properties in this class of compounds are due to the non-innocent character originating from their quasi-aromaticity and strong π-electron donor ability due to the involvement of sulfur atoms. 14–18 The avid interest in such molecule based metal complexes stems from the following reasons: (a) they have tuneable steric and electronic structures, (b) adaptable intrinsic activity, (c) clearly defined catalytic mechanisms, (d) high product selectivity and (e) excellent atomic economy. 15 Inspired by these aspects associated with metal dithiolenes/dithiolates, we recently have explored their utility as molecular electrocatalysts for the oxygen evolution reaction (OER).…”

“…14–18 The avid interest in such molecule based metal complexes stems from the following reasons: (a) they have tuneable steric and electronic structures, (b) adaptable intrinsic activity, (c) clearly defined catalytic mechanisms, (d) high product selectivity and (e) excellent atomic economy. 15 Inspired by these aspects associated with metal dithiolenes/dithiolates, we recently have explored their utility as molecular electrocatalysts for the oxygen evolution reaction (OER). 16 In view of the attractive electrocatalytic applications of metal complexes, we recently have explored the supramolecular frameworks and electrocatalytic properties of two new structurally diverse tertiary phosphane-appended nickel( ii ) and copper( i ) ethoxycyclobutenedione-4-thiolates.…”

Multi-functional photocatalytic systems for solar fuel production

“…In contrast, an extensive effort has been devoted to clarifying catalytic mechanisms of homogeneous water oxidation, proton or CO 2 reduction. 9–19,35–48 Dual functional homogeneous catalysts have been developed for photochemical synthesis. 49–54 However, multi-functional homogeneous photocatalysts have been less developed for photocatalytic water oxidation combined with proton or CO 2 reduction.…”

“…Then, immobilization of different molecular catalysts on solid-state supports for solar fuel production will be described to provide a system displaying dual catalytic function, enhanced selectivity and simplified identification of the active species, while also facilitating product isolation and catalyst recycling. 14,40,41,55 Finally, construction of multi-functional catalytic systems is discussed for solar-driven fuel production from water. 27,41–57…”