Oxygen evolution reaction (OER) is an important half-reaction in energy conversion and storage devices such as electrolysis of water and secondary metal-air batteries. However, OER has a high reaction energy barrier and slow kinetics, and traditional electrocatalysts based on precious metals are expensive Therefore, there is an urgent need to develop new non-noble metal electrocatalysts. Amorphous electrocatalysts have abundant active centers, while crystalline catalysts exhibit good electron transfer characteristics. Reasonable design and optimization of the microstructure and composition of the electrocatalyst and the construction of two-phase nanocomposites provide more possibilities for improving the performance of OER; the combination of in-situ characterization technology and theoretical calculations is expected to further reveal the catalytic mechanism of OER.
Recently, the research team of Wang Jiacheng, a researcher at the Shanghai Institute of Ceramics, Chinese Academy of Sciences, has prepared a crystal-amorphous two-phase structure (Ni1.5Sn@triMPO4) for use in electrocatalytic OER. Related research results were published on Angewandte Chemie International Edition with the title A glass-ceramic with accelerated surface reconstruction toward the efficient oxygen evolution reaction, and were selected as Very Important Paper (VIP). Wang Jiacheng, Ma Ruguang, associate researcher of Shanghai Institute of Ceramics, and Liu Danmin, a researcher of Beijing University of Technology, are the co-corresponding authors of the paper.
The research started with SnFeNi perovskite hydroxide (previous work published in J. Mater. Chem. A. 2020, 8, 5919-5926), and obtained Ni1.5Sn@triMPO4 glass ceramics through low-temperature phosphating. Further use of electrochemical activation to precipitate part of the cation Sn4+ and anion PO43-, accelerate the surface reconstruction of the glass ceramics, and generate an active layer (Ni(Fe)OOH- with intrinsic oxygen vacancies VO and residual PO43-) on the catalyst surface VO-PO4). Compared with the control sample, the overpotential of the restructured glass-ceramics is significantly reduced, and the OER kinetics is enhanced, which is comparable to some non-noble metal electrocatalysts. Theoretical calculations show that the low vacancy formation energy of Sn and the high adsorption energy of PO43- on the VO site accelerate the surface reconstruction of glass-ceramics; the remaining PO43- and VO sites lead to the charge transfer of adjacent Ni atoms, causing The center of the d-band is closer to the Fermi level. This charge distribution optimizes the adsorption of OH* and OOH* intermediates on metal oxyhydroxides, and improves OER activity. This study proves the structural advantages of glass-ceramics in promoting surface reconstruction and provides new ideas for the design of advanced electrocatalysts.
The research work was funded by the National Natural Science Foundation of China and the Shanghai Science and Technology Commission.
Figure 1. Glass-ceramic accelerates surface reconstruction and promotes OER reaction
Figure 2. The glass ceramics with dual-phase structure were synthesized by low-temperature phosphating method, combined with XRD, XPS, HRTEM, EDS-Mapping and other technologies, it is proved that the crystalline phase is Ni1.5Sn nanoparticles and the amorphous phase is triMPO4 Phosphate
