Roles of Metal Oxide Nanostructure-Based Substrates in Sustainable Electrochemical Water Splitting: Recent Development and Future Perspective

Abstract

Increasing energy demand to find everlasting and eco-friendly resources is now mainly dependent on green hydrogen production technology. Water electrolysis has been regarded as a clean route for green H 2 production with zero carbon emission, but different bottlenecks in the development of electrodes impeded its realization. Recently, transition metal oxides (TMO) have gained tremendous attention as suitable cathodes and anodes due to their sustainability under harsh conditions, high redox features, maximum supportive capability, easy modulation in valence states, and enhanced electrical conductivity. In this review, we have highlighted the role of transition metal oxides as active and supported sites for electrochemical water splitting. We have proposed different perspectives for the rational design of TMO-based electrode materials, i.e., electronic state modulation, modification of the surface structure to control the aerophobicity and hydrophilicity, acceleration of the charge and mass transport, and stability of the electrocatalyst in harsh environments. We have systemically discussed the insights into the relationship among catalytic activity, certain specified challenges, research directions, and perspectives of electrocatalysis of the OER and HER.

Protective Cerium Oxide Coating Promoted Ce‐Doping and Reconstruction of High‐Valence NiFe Sulfide toward Robust Overall Water Splitting

“…However, in the Ni─O─Ce unit, the electronic configuration of Ce 4+ is (Xe)4f 0 ; thus, Ce 4+ exists as a vacant orbital (Figure 4g). The latter interacts with the bridging O 2− via 𝜋-donation, triggering partial charge transfer from Ni 2+ to Ce 4+ , converting Ni 2+ (t 2g 6 e g 2 ) into Ni 3+ (t 2g 6 e g 1 ). [23] Typically, a JT distortion is observed for Ni 3+ , resulting from an unsymmetrically filled electronic degenerate orbital.…”

Metal–Organic Framework-Derived FeCo2S4/Co3O4 Heterostructure with Enhanced Electrocatalytic Performance for Oxygen Evolution and Hydrogen Evolution Reactions

“…T.M. sulfides, , nitrides, , phosphides, , oxides , and carbides , have shown tremendous promise as HER and OER catalysts in both acidic and alkaline conditions. While sulfides and phosphides have generally furnished excellent HER performance, the better OER performance has been associated with T.M.…”

Electronic and Structural Modification of Three-Dimensional Porous NiCo@NF as a Robust Electrocatalyst for CO2 Emission-Free Methanol Upgradation to Boost Hydrogen Co-production

“…In recent years, researchers have been working on the structural and electronic modulation of an electrocatalyst to enhance its activity, selectivity, and durability for MOR-assisted alkaline water electrolysis. − Electronic modulation is considered an efficient strategy to modulate the chemisorption energy of active sites by varying the density of states (DOS) near the Fermi level that selectively bind with the intermediates having more compatible orbital energy. Meanwhile, surface structural modulation has been used to decrease charge diffusion and ionic pathways between active sites . However, it is a critical challenge to fit the structural and electronic features into a single catalyst to sustain the high output at low input voltage.…”

“…Meanwhile, surface structural modulation has been used to decrease charge diffusion and ionic pathways between active sites. 24 T h i s c o n t e n t i s However, it is a critical challenge to fit the structural and electronic features into a single catalyst to sustain the high output at low input voltage. Cobalt-based catalysts such as NiCo@Cu, 25 NiCo(OH) 2 /NF, 26 NiCo/NiO-CoO, 27 Gd-CoB@TiO 2 , 28 CoP@NiCo-LDH, 29 Co-Cu-MOF, 15 and CuO/Co (OH) 2 30 reveal remarkable MOR activity.…”