Quan Quan,Zhang Yuxuan,Li Haifan,Wang Wei,Xie Pengshan,Chen Dong,Wang Weijun,Meng You,Yin Di,Li Yezhan,Song Dongyuan,Chen Lijie,Li Shaohai,Yang Cheng,Yanagida Takeshi,Wong Chun-Yuen,Yip SenPo,Ho Johnny C.
Maximizing metal-substrate interactions by self-reconstruction of coadjutant metastable phases can be a delicate strategy to obtain robust and efficient high-density single-atom catalysts. Here, we prepare high-density iridium atoms embedded ultrathin CoCeOOH nanosheets (CoCe-O-Ir SA ) by the electrochemistry-initiated synchronous evolution between metastable iridium intermediates and symmetry-breaking CoCe(OH) 2 substrates. The CoCe-O-Ir SA delivers an overpotential of 187 mV at 100 mA cm −2 and a steady lifespan of 1000 h at 500 mA cm −2 for oxygen evolution reaction. Furthermore, the CoCe-O-Ir SA is applied as a robust anode in an anion-exchange-membrane water electrolysis cell for seawater splitting at 500 mA cm −2 for 150 h. Operando experimental and theoretical calculation results demonstrate that the reconstructed thermodynamically stable iridium single atoms act as highly active sites by regulating charge redistribution with strongly p - d - f orbital couplings, enabling electron transfer facilitated, the adsorption energies of intermediates optimized, and the surface reactivity of Co/Ce sites activated, leading to high oxygen evolution performance. These results open up an approach for engineering metastable phases to realize stable single-atom systems under ambient conditions toward efficient energy-conversion applications.
Oxygen evolution reaction (OER) remains the bottleneck of many energy transformation and storage technologies due to the sluggish kinetics. Transition-metal (TM) hydroxide nanosheets with high-valent TM ions possess high intrinsic catalytic activity toward OER. Herein, by taking advantage of the inductive effect, this work presents a facile and universal strategy to fabricate atomic iridium (Ir) incorporated TM hydroxide nanosheets as highly active OER electrocatalysts . As a representative, the fabricated Ir-Ni(OH) 2 (4 wt% Ir) exhibits remarkable OER performance with a low overpotential (235 mV at 10 mA cm −2 ), a small Tafel slope (58.4 mV dec −1 ), and excellent durability (60 h) in alkaline solution, significantly outperforming the benchmark IrO 2 and Ni(OH) 2 . Mechanism studies unveil that the inductive effect between Ni and Ir endows Ni(OH) 2 with high-valent Ni species, which facilitate the adsorption of nucleophilic intermediates and boost the OER activity and long-term stability of Ir-Ni(OH) 2 . More importantly, the reported strategy could be extended to synthesize other monometallic/bimetallic TM hydroxide nanosheets (Co, CoMn) as highly efficient OER electrocatalysts. This work should pave a universal and promising avenue to rationally design and controllably synthesize efficient yet robust OER electrocatalysts in energy-related fields.
The development of proton exchange membrane water electrolyzers (PEMWEs) relies on the active and robust iridium (Ir)-based electrocatalysts for oxygen evolution reaction (OER) under acidic conditions. Loading low-content Ir with cobalt oxide (Co 3 O 4 ) nanocrystals has attracted considerable attention due to its reasonable price and high activity. However, their unsatisfying stability in acidic environments hinders their application. Herein, Ir atoms have been distributed differentiatedly in Co 3 O 4 to enhance the durability for acidic OER. Compared to the Co 3 O 4 with Ir uniformly doping (Ir B -Co 3 O 4 ), the reduced bulk Ir content in Ir S -Co 3 O 4 alleviates the electrooxidation process and facilitates the adsorbate-based pathway, thus stabilizing the structure of oxides during acidic OER. The optimized Ir S -Co 3 O 4 catalyst exhibits high mass activity of 1059.9 A g Ir −1 at 1.60 V vs RHE (779.6 A g Ir −1 for Ir B -Co 3 O 4 ). Importantly, Ir S -Co 3 O 4 possesses great stability without obvious activity loss after 20 h of continuous operation at 10 mA cm −2 , while the Ir B -Co 3 O 4 and Co 3 O 4 is deactivated within 8 and 4 h, respectively. This work provides a mechanistic understanding for designing lower-cost, active, and stable electrocatalysts containing a trace of Ir for OER.
危险品化学品经营许可证（带存储）