Proton exchange membrane water electrolyzers (PEMWEs) driven by renewable electricity provide a facile path toward green hydrogen production, which is critical for establishing a sustainable hydrogen society. The high working potential and the corrosive environment pose severe challenges for developing highly active and durable electrocatalysts for the oxygen evolution reaction (OER). To date, iridium (Ir)‐based materials, largely metallic Ir and Ir‐based oxides, are the most suitable OER electrocatalysts for PEMWEs due to their balanced activity and durability. Tremendous efforts have been devoted to improving the specific activity of Ir species to reduce the cost; however, advances in enhancing the durability of Ir‐based electrocatalysts are rather limited. In this review, the recent research progress on tackling the stability issues of Ir‐based OER electrocatalysts in acid media is summarized, aiming to provide inspiration for designing highly active and stable Ir‐based electrocatalysts. The OER mechanism and the associated failure modes of active Ir species are summarized. Then, mechanistic studies on the dissolution behavior of Ir species and experimental attempts on enhancing the durability of Ir‐based electrocatalysts are discussed. The personal perspectives for future studies on Ir‐based OER electrocatalysts are also provided.

No abstract

Developing new optimized bifunctional photocatalyst is of great significant for achieving the high-performance photo-assisted Li-O 2 batteries. Herein, a novel bifunctional photo-assisted Li-O 2 system is constructed by using siloxene nanosheets with ultra-large size and few-layers due to its superior light harvesting, semiconductor characteristic, and low recombination rate. An ultra-low charge potential of 1.90 V and ultra-high discharge of 3.51 V have been obtained due to the introduction of this bifunctional photocatalyst into Li-O 2 batteries, and these results have realized the round-trip efficiency up to 185 %. In addition, this photo-assisted Li-O 2 batteries exhibits a high rate (129 % round-trip efficiency at 1 mAcm À2 ), a prolonged cycling life with 92 % efficiency retention after 100 cycles, and the highly reversible capacity of 1170 mAh g À1 at 0.75 mA cm À2 . This work will open the vigorous opportunity for high-efficiency utilization of solar energy into electric system.

Borophene with 4 layers and lateral size of 5.05 μm can be prepared by liquid phase exfoliation.