Perovskite/Carbon Composites: Applications in Oxygen Electrocatalysis

Abstract

Oxygen electrocatalysis, i.e., oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), plays an extremely important role in oxygen-based renewable-energy technologies such as rechargeable metal-air batteries, regenerative fuel cells and water splitting. Perovskite oxides have recently attracted increasing interest and hold great promise as efficient ORR and OER catalysts to replace noble-metal-based catalysts, owing to their high intrinsic catalytic activity, abundant variety, low cost, and rich resources. The introduction of perovskite-carbon interfaces by forming perovskite/carbon composites may bring a synergistic effect between the two phases, thus benefiting the oxygen electrocatalysis. This review provides a comprehensive overview of recent advances in perovskite/carbon composites for oxygen electrocatalysis in alkaline media, aiming to provide insights into the key parameters that influence the ORR/OER performance of the composites, including the physical/chemical properties and morphologies of the perovskites, the multiple roles of carbon, the synthetic method and the synergistic effect. A special emphasis is placed on the origin of the synergistic effect associated with the interfacial interaction between the perovskite and the carbon phases for enhanced ORR/OER performance. Finally, the existing challenges and the future directions for the synthesis and development of more efficient oxygen catalysts based on perovskite/carbon composites are proposed.

Perovskite Electrocatalysts for the Oxygen Reduction Reaction in Alkaline Media

“…In addition to activity, the carbon in composite electrodes may also affect the stability. Carbon may corrode or erode at oxidative potentials [98], which is a known problem for the stability of catalyst layers made from inks or slurries. The design of perovskite-carbon hybrid systems [98][99][100][101][102] is a possible avenue to make composite electrodes more robust so that catalyst stability is decoupled from catalyst activity.…”

“…The design of perovskite-carbon hybrid systems [98][99][100][101][102] is a possible avenue to make composite electrodes more robust so that catalyst stability is decoupled from catalyst activity. Synergetic effects between carbon supports and perovskite catalysts is a very active field of research and the reader is referred to a recent review for additional discussion [98].…”

Strategy for Enhancing Interfacial Effect of Bifunctional Electrocatalyst: Infiltration of Cobalt Nanooxide on Perovskite

“…Early studies have confirmed that these strains (compressive and tensile) at the interface can induce the changes in the electron population of the d-orbital of transition metals, resulting in the change of catalytic properties involving adsorption strength of oxygen. [4,[21][22][23] In this regard, we focused on a new approach to control the catalytic activity by intentionally applying the strain and ligand effect through infiltration technique. The perturbation in the electronic structure by the ligand effect can alter the binding strength between oxygen species and metal oxides at the surface of the electrocatalyst.…”

A Composite Catalyst Based on Perovskites for Overall Water Splitting in Alkaline Conditions

“…[14,15] The catalytically active transition metals nanoparticles, such as Pd, Ru, Pt, Ag, Co, Ni, and Fe, are exsolved as nanoparticles from the A/B site of perovskite oxides backbone under a reducing atmosphere. [21,22] As an approach to enhance the electrical conductivity, the perovskite/carbon composites have been suggested since the carbon is one of the excellent conducting materials at room temperature. [16][17][18] This operando manufacture way can spontaneously lead to the formation of ordered layered oxygen deficiency and the yield segregation of massively and finely dispersed metallic nanoparticles.…”