Earth-abundant metal complexes as catalysts for water oxidation; is it homogeneous or heterogeneous?

Abstract

MINIREVIEW This journal isRecent developments in the oxidation of water to dioxygen using metal complexes as catalysts or precatalysts are represented at the side of the conversion of homogeneous catalysts into nanoparticles or heterogeneous one during the oxidation reaction of water. Homogeneous catalysts are advantageous within the careful design and elucidation of the mechanisms for the catalytic water oxidation. In distinction, the uses of heterogeneous catalysts in water oxidation are advantageous for sensible applications as a result of their robust catalytic activity. Though detailed studies on homogeneous and heterogeneous water oxidation reactions are performed rather severally, the connection of homogeneous catalysts with heterogeneous one is changing into an additional requirement for the event of economic attractive water oxidation catalysts (WOCs). This minireview focuses on the aspects if the particular catalysts for the oxidation of water are homogeneous or heterogeneous.

Homogeneous and Heterogeneous Photocatalytic Water Oxidation by Persulfate

“…As mentioned above,d etermination of the true catalyst for the water oxidation to dioxygenh as become an important issue because extra caution needs to be taken to clarify whether nanoparticles are produced from the homogeneous metal complexes throughout the oxidation reactions, acting as the actualc atalysts or not. [81][82][83][84][85][86][87][88][89][90][91][92][93] Water-soluble cobalt complexes (Figure 1a-d) have been reportedt oa ct as precatalysts rather than actual catalysts in the photocatalytic water oxidation by persulfate with [Ru(bpy) 3 ] 2 + . [94] The TON and yield of O 2 are listed in Table 2.…”

Electrocatalytic water oxidation by a Ni(ii) salophen-type complex

“…2 Homogenous water oxidation catalysts are useful in the examination of reaction mechanisms and identication of the active intermediates which will give an opportunity for the precise designing of catalysts, while water insoluble catalysts can allow for easier post-reaction separation and recyclability. 3 Water splitting can be divided two half-reactions: proton reduction (2H + + 2e / H 2 ) and water oxidation (2H 2 O / 4H + + O 2 + 4e). Water oxidation is a slow electrochemical reaction with a high potential of about 1.23 eV.…”

Synthesis and Physicochemical Properties of Ruthenium(II) Complexes Having Pentadentate Scaffolds: Water Oxidation Activity and Deactivation Pathway

“…The 1 st row transition metal ions, being kinetically labile in general, often undergo easy ligand decoordination/hydrolysis in aqueous medium and thus lose the molecular nature very easily . This leads to the formation of metal oxides/hydroxides nanoparticles which generally exhibit catalytic activity; therefore, the characterization of the active species and mechanistic investigations with these complexes become more complicated . However, ruthenium, being a 4d element, nicely keeps the balance between kinetic lability and inertness and maintains the molecular nature at a very wide range of pH.…”