Heterogeneous Electrocatalyst with Molecular Cobalt Ions Serving as the Center of Active Sites

Abstract

Molecular Co ions were grafted onto doped graphene in a coordination environment, resulting in the formation of molecularly well-defined, highly active electrocatalytic sites at a heterogeneous interface for the oxygen evolution reaction (OER). The S dopants of graphene are suggested to be one of the binding sites and to be responsible for improving the intrinsic activity of the Co sites. The turnover frequency of such Co sites is greater than that of many Co-based nanostructures and IrO catalysts. Through a series of carefully designed experiments, the pathway for the evolution of the Co cation-based molecular catalyst for the OER was further demonstrated on such a single Co-ion site for the first time. The Co ions were successively oxidized to Co and Co states prior to the OER. The sequential oxidation was coupled with the transfer of different numbers of protons/hydroxides and generated an active Co═O fragment. A side-on hydroperoxo ligand of the Co site is proposed as a key intermediate for the formation of dioxygen.

Design of Efficient Bifunctional Oxygen Reduction/Evolution Electrocatalyst: Recent Advances and Perspectives

“…[27,[109][110][111] (Figure 13a). [109] They found that a volcano-like trend between OER activity (potential at 2 mAcm −2 ) for NG-M and corresponding d electron numbers of M x+ (Figure 13b) (Figure 13f).…”

Reduced graphene oxide‐based materials for electrochemical energy conversion reactions

“…Anchoring the molecular catalysts onto carbon‐based templates would be one promising approach to overcome these shortcomings because carbon‐based templates can provide a high surface area, excellent electrical conductivity, and numerous surface functional sites to immobilize molecular catalysts with covalent bonds. Wang et al reported Co‐based molecular OER electrocatalyst which is anchored on the heteroatom‐doped rGO. Electrochemical analysis revealed that the heteroatoms (S, N, and O atoms) in rGO play a crucial role as the binding sites of Co 2+ ions.…”

Boosting Electrochemical Water Oxidation with Metal Hydroxide Carbonate Templated Prussian Blue Analogues

“…[3] Though noble metal catalysts like IrO 2 and RuO 2 produce good activity in the OER, scarcity and high cost limits their large-scale applications. [5,6] In particular,m etal-organic framework (MOF)derived catalyst systems have been developed with improved electrochemical activity due to availability of the increased amount of the active sites. [5,6] In particular,m etal-organic framework (MOF)derived catalyst systems have been developed with improved electrochemical activity due to availability of the increased amount of the active sites.…”

“…[4] In this respect, efficient water oxidation catalysts with earth-abundant elements attain major attention in recent years. [5,6] In particular,m etal-organic framework (MOF)derived catalyst systems have been developed with improved electrochemical activity due to availability of the increased amount of the active sites. [7] Recently,P russian blue analogues (PBAs) have been extensively studied as anew class of materials for the energy-related applications such as batteries, supercapacitors,oro xygen reduction reactions.…”