New Undisputed Evidence and Strategy for Enhanced Lattice‐Oxygen Participation of Perovskite Electrocatalyst through Cation Deficiency Manipulation

Abstract

Oxygen evolution reaction (OER) is a key half-reaction in many electrochemical transformations, and efficient electrocatalysts are critical to improve its kinetics which is typically sluggish due to its multielectron-transfer nature. Perovskite oxides are a popular category of OER catalysts, while their activity remains insufficient under the conventional adsorbate evolution reaction scheme where scaling relations limit activity enhancement. The lattice oxygen-mediated mechanism (LOM) has been recently reported to overcome such scaling relations and boost the OER catalysis over several doped perovskite catalysts. However, direct evidence supporting the LOM participation is still very little because the doping strategy applied would introduce additional active sites that may mask the real reaction mechanism. Herein, a dopant-free, cation deficiency manipulation strategy to tailor the bulk diffusion properties of perovskites without affecting their surface properties is reported, providing a perfect platform for studying the contribution of LOM to OER catalysis. Further optimizing the A-site deficiency achieves a perovskite candidate with excellent intrinsic OER activity, which also demonstrates outstanding performance in rechargeable Zn-air batteries and water electrolyzers. These findings not only corroborate the key role of LOM in OER electrocatalysis, but also provide an effective way for the rational design of better catalyst materials for clean energy technologies.

Entwined Co(OH)2 In Situ Anchoring on 3D Nickel Foam with Phenomenal Bifunctional Activity in Overall Water Splitting

“…Since cobalt is earth abundant, Co-based composites with properties very near to state-of-art catalysts are potential materials to replace Pt/Pd-based catalysts. − The oxygen evolution reaction (OER) (1.23 V) shows severe barrier relative to HER (0 V) owing to sluggish kinetics originating from multistep electron transfer: − OER involved OH – breakage, OH – adsorption, and O–O formation. − Thomas et al . volcano plot (OER) consists of metal oxides based on Δ G O – Δ G OH , where Co-based catalysts are situated at the top, especially spinel-structured metal oxides (MCo 2 O 4 , M–Zn, Fe, Ni, Co, Cu, and Mn).…”

Unraveling the Role of Defects in Electrocatalysts for Water Splitting: Recent Advances and Perspectives

“…156,230,231 The operation on the basis of the LOM involving direct O−O coupling was claimed to be capable of bypassing the inherent linear scaling relation (approximately constant difference of ΔE HOO* − ΔE HO* of 3.2 eV) in the AEM, in which the minimum theoretical overpotential remains high (0.37 V) for the ideal case because of the mutual competition between O− H bond cleavage and *OOH formation. 217,232,233 The defect engineering has been found to result in a reaction mechanism transition between the AEM and LOM (Figure 8g). 155,234 For instance, a mechanism study was carried out on La 1−x Sr x CoO 3−δ (0 ≤ x ≤ 1), where a transition from the AEM to LOM was predicted by substituting Sr into the lattice with a higher content.…”

Carbon nanotubes anchored onto hollow carbon for efficient oxygen reduction

“…The rapid development and deployment of advanced energy storage and conversion have been eagerly prompted to cope with the emerging increasing energy demand. Among these, commercial proton-exchange membrane fuel cells and metal-air batteries are considered as the next generation of clean energy conversion devices due to their high efficiency, environmental protection, and sustainability [1][2][3][4][5][6]. Given that cathodic oxygen reduction reaction (ORR) is highly susceptible to high activation barriers and sluggish kinetics, low-cost and durable catalysts must be urgently developed to improve the intrinsic activity [7,8].…”