Perspectives on the development of highly active, stable, and cost‐effective OER electrocatalysts in acid

Abstract

Polymer electrolyte membrane water electrolysis (PEMWE) is an attractive hydrogen energy production technology that offers various advantages such as compact design, high operating pressure, high current densities, and high hydrogen gas purity. However, PEMWE still faces several critical challenges, particularly with respect to the oxygen evolution reaction (OER) at the anode. Highly active, corrosion‐resistant electrocatalytic materials are required for the acidic OER owing to its sluggish kinetics involving four‐electron transfer under harsh anodic potentials. To date, IrO2‐ or RuO2‐based noble metal electrocatalysts have been employed as commercial acidic OER electrocatalysts for PEMWE. However, they remain inadequate in terms of satisfying the industrial activity/stability‐related requirements. Above all, the two noble metals are too rare and expensive, which significantly inhibits widespread commercialization of PEMWE. Therefore, low‐cost, highly active, and highly stable OER electrocatalysts that can operate in acidic media must be urgently developed. This review paper presents various state‐of‐the‐art strategies employed to address the aforementioned issues by classifying them according to objectives such as improving activity, enhancing stability, and reducing cost. Then, finally, we summarize major tasks and strategies to overcome them and put forward a few issues in this field.

Guided Design of Efficient Oxygen Evolution Catalysts Using Patent Analysis

“…In catalyst preparation (Figure 1g), calcination, solvothermal, wet chemistry, and electrochemical methods are the most commonly used approaches for synthesizing the OER catalysts. Among them, calcination and solvothermal methods are widely utilized due to their process stability, but they suffer from the drawback of lengthy preparation cycles, especially when a catalyst is prepared using both solvothermal and calcination techniques, with most processes exceeding 48 h. Efficient commercial OER catalysts usually need to have the following characteristics: excellent catalytic activity and stability, 26 stable process with a short preparation time, green and nonpolluting, 14 and low cost 26 (Figure 2). Oxides and hydroxides of NiFe have been extensively studied for their own excellent OER properties and can be used as substrates to provide a stable catalysts.…”

“…Efficient commercial OER catalysts usually need to have the following characteristics: excellent catalytic activity and stability, 26 stable process with a short preparation time, green and nonpolluting, 14 and low cost 26 ( Figure 2 ). Oxides and hydroxides of NiFe have been extensively studied for their own excellent OER properties and can be used as substrates to provide a stable catalysts.…”

Carbon material with high pyridine/graphite nitrogen content: an efficient electrocatalyst for the oxygen reduction reaction

“…The evolution of society and industry has underscored the imperative of advancing green and sustainable energy initiatives, becoming a pivotal focus in both corporate development and scientific research. 1–4 Zn–air batteries have garnered significant interest, attributed to their superior performance, absence of pollution, cost-efficiency, and eco-friendliness. 5–9 While smaller Zn–air batteries have been integrated into portable devices such as hearing aids and navigation lights, 10–12 they predominantly rely on the noble metal, Pt, to facilitate the otherwise sluggish cathodic oxygen reduction reaction (ORR).…”

“…Recent investigations have elucidated that N atoms doped in carbon structures induce charge redistribution within the π-conjugation system of the carbon framework. 3 This redistribution alters the adsorption or desorption energy of the intermediate species involved in the ORR, thereby reducing the reaction energy barrier and facilitating the swift progression of the reaction. 31 Typically, in N-doped carbon-based ORR catalysts, N atoms are present in four distinct configurations: pyridinic-N, graphitic-N, pyrrolic-N, and oxidized-N. 32–34 Oxidized-N assumes an sp 3 hybridization, whereas pyrrolic-N, pyridinic-N, and graphitic-N adopt an sp 2 hybridized state.…”

Defect Engineering of RuO2 Aerogel for Efficient Acidic Water Oxidation

“…Presently, OER catalysts compatible with PEMWE technology predominantly depend on iridium (Ir) and ruthenium (Ru)-based materials. , Ruthenium dioxide (RuO 2 ) is widely recognized as an acidic OER electrocatalyst due to its remarkable activity and relatively abundant reserves. However, the irreversible conversion of RuO 2 to soluble RuO 4 species in acidic media severely compromises its stability, which is closely linked to the reaction process. − Currently, the prevailing OER mechanisms can be primarily classified into two pathways, namely, the lattice oxygen mechanism (LOM) and the adsorption evolution mechanism (AEM), depending on the origin of oxygen molecules in the reaction products. − The AEM pathway is distinct from the LOM pathway in that it does not consume lattice oxygen or produce oxygen vacancies, thereby maintaining the structural integrity of the catalyst during the reaction and resulting in enhanced stability. − Clearly, the structural-stability optimization of the catalyst hinges on maximizing the dominance of the AEM . To this end, defect engineering, including atomic vacancies (RuO 2 /SnO 2 ), interstitial (C-RuO 2 –RuSe), solute atoms (Ru 0.5 Ir 0.5 O 2 ), amorphous/crystalline interface (Am–Ir 1 Ru 3 O 8 ), and so on, has received considerable attention. − It is worth noting that the presence of defects can disrupt the initial structural arrangement, therefore serving as active sites to alter the pathway of the reaction process.…”