Self-supported amorphous iridium oxide catalysts for highly efficient and durable oxygen evolution reaction in acidic media

Advanced Ir-Based Alloy Electrocatalysts for Proton Exchange Membrane Water Electrolyzers

Proton exchange membrane water electrolyzer (PEMWE) coupled with renewable energy to produce hydrogen is an important part of clean energy acquisition in the future. However, the slow kinetics of the oxygen evolution reaction (OER) hinder the large-scale application of PEM water electrolysis technology. To deal with the problems existing in the PEM electrolyzer and improve the electrolysis efficiency, substantial efforts are invested in the development of cost-effective and stable electrocatalysts. Within this scenario, the different OER reaction mechanisms are first discussed here. Based on the in-depth understanding of the reaction mechanism, the research progress of low-iridium noble metal alloys is reviewed from the aspects of special effects, design strategies, reaction mechanisms, and synthesis methods. Finally, the challenges and prospects of the future development of high-efficiency and low-precious metal OER electrocatalysts are presented.

Boosting electrocatalytic performance via electronic structure regulation for acidic oxygen evolution

High-purity hydrogen produced by water electrolysis has become a sustainable energy carrier. Due to the corrosive environments and strong oxidizing working conditions, the main challenge faced by acidic water oxidation is the decrease in the activity and stability of anodic electrocatalysts. To address this issue, efficient strategies have been developed to design electrocatalysts toward acidic OER with excellent intrinsic performance. Electronic structure modification achieved through defect engineering, doping, alloying, atomic arrangement, surface reconstruction, and constructing metal-support interactions provides an effective means to boost OER. Based on introducing OER mechanism commonly present in acidic environments, this review comprehensively summarizes the effective strategies for regulating the electronic structure to boost the activity and stability of catalytic materials. Finally, several promising research directions are discussed to inspire the design and synthesis of high-performance acidic OER electrocatalysts.

Recent advances in iridium-based catalysts with different dimensions for the acidic oxygen evolution reaction

Proton exchange membrane (PEM) water electrolysis is considered a promising technology for green hydrogen production, and iridium (Ir)-based catalysts are the best materials for anodic oxygen evolution reactions (OER) owing to their high stability and anti-corrosion ability in a strong acid electrolyte. The properties of Ir-based nanocatalysts can be tuned by rational dimension engineering, which has received intensive attention recently for catalysis ability boosting. To achieve a comprehensive understanding of the structural and catalysis performance, herein, an overview of the recent progress was provided for Ir-based catalysts with different dimensions for the acidic OER. The promotional effect was first presented in terms of the nano-size effect, synergistic effect, and electronic effect based on the dimensional effect, then the latest progress of Ir-based catalysts classified into zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D) and three-dimensional (3D) catalysts was introduced in detail; and the practical application of some typical examples in the real PEM water electrolyzers (PEMWE) was also presented. Finally, the problems and challenges faced by current dimensionally engineered Ir-based catalysts in acidic electrolytes were discussed. It is concluded that the increased surface area and catalytic active sites can be realized by dimensional engineering strategies, while the controllable synthesis of different dimensional structured catalysts is still a great challenge, and the correlation between structure and performance, especially for the structural evolution during the electrochemical operation process, should be probed in depth. Hopefully, this effort could help understand the progress of dimensional engineering of Ir-based catalysts in OER catalysis and contribute to the design and preparation of novel efficient Ir-based catalysts.