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Hydrogen energy is a well-respected clean renewable energy technology. The bottleneck that restricts the development of this technology is how to design and develop low-cost, high-efficiency electrocatalysts. In response to this bottleneck, Professor Xiong Yujie of the University of Science and Technology of China has designed and developed a series of ternary alloy PtFeCo nanostructures with adjustable chemical compositions and tridentate stars. While reducing the amount of precious metal platinum, a significant increase in electricity has been achieved. Catalytic hydrogen evolution reaction activity. The research results were recently published in Advanced Materials 2016 (28, 2077) and were reported by Materials Views China, a Wiley-owned Chinese academic news website. The co-first authors of the dissertation were PhD student Du Nana, senior engineer Wang Chengming and doctoral student Wang Yujun.
Studies have shown that the key to improving the electrocatalytic activity of materials lies in the regulation of surface structure and electronic structure. However, how to synchronize these two parameters is a major challenge in the design and preparation of related materials. In recent years, Xiong Yujie’s research group has developed a type of interface charge polarization mechanism for catalyst design. Based on the interface formation method with controllable atomic precision, the number of active sites and the degree of activity can be adjusted through interface dimension control (J. Am Chem. Soc. 2014, 136, 14650; Angew. Chem. Int. Ed. 2014, 53, 12120; Angew. Chem. Int. Ed. 2015, 54, 14810).
In this work, the researchers further extended the mechanism of action to the inter-atomic charge polarization in the alloy system, which is used to regulate the electron density of the Pt catalytic sites, thereby obtaining a tunable electronic structure. They first synthesized a series of ternary alloy PtFeCo nanostructures, which not only achieved precise control of the proportion of Fe and Co atoms in the platinum-based nanoalloy crystal lattice, but also constructed a trifurcated star-like structure with high catalytic activity for multi-angle systems. The structure-activity relationship in the electrocatalytic hydrogen evolution reaction provides an excellent platform. The systematic study shows that the simultaneous optimization of electronic structure and surface structure in nano-alloys plays a crucial role in the electrocatalytic performance of HER. Based on theoretical calculations, its co-author Jiang Jun's group revealed that the introduction of Co atoms in the alloy lattice can induce inter-atomic charge polarization, regulate atomic electron density, and simultaneously modulate the d-band center of the metal Pt atomic sites. It helps to increase the catalytic site activity. Based on this knowledge, the researchers established a structure-activity relationship between the chemical composition of the alloy and the electrocatalytic HER properties.
Based on this structure-activity relationship, the researchers obtained a Pt81Fe28Co10 trigeminal nanostructure with a current density as high as 1325 mA cm-2 at a voltage of -400 mV, which is more than four times that of commercially available platinum-carbon catalysts, far superior to other homologous platinum groups. catalyst. At the same time, the stability of the catalyst is further improved compared to other platinum-based catalysts. The ternary alloy PtFeCo trigeminate star-like nanostructure construction, from the experimental and theoretical level clearly illustrates the triad integration mechanism based on elemental composition, electronic structure and surface structure, and is a rational design for low-cost, high-performance alloy catalysts. With the construction opened up a new path. The idea of ​​lattice engineering proposed in this study will expand people's ability to control the "microscopic engine" of electron motion in electrical energy-chemical transformation, and it will promote the design of electrocatalysts with atomic precision.
The research was funded by the Ministry of Science and Technology's "973" program, the National Natural Science Foundation of China, the National Youth Talents Program, the 100-person plan of the Chinese Academy of Sciences, the Advanced User Fund of the Hefei University Science Center, and the China University of Science and Technology major project development fund.
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