First Author:Xue Yanrong, Zhao Jiwu
Corresponding Author: Lu Xu
Correspondence: King Abdullah University of Science and Technology (KAUST).
**doi：
Water electrolysis to hydrogen is a clean and efficient energy production method, among which proton exchange membrane water electrolysis hydrogen production technology (PEMWE) has attracted extensive attention from the industry due to its compact structure, high working current density and fast start-stop technology. However, a key problem faced by commercial PEMWE is that the anode often requires the use of expensive iridium-based catalysts, so it is important to develop non-iridium oxygen evolution (OER) catalysts with low IR content or more economical content. Ruthenium oxide (RuO2) is considered to be the most promising iridium-based catalyst alternative due to its relatively low level and excellent OER catalytic activity. However, there is a coordination unsaturated lattice O on the surface of RuO2, which makes it susceptible to excessive oxidation at high potentials, resulting in the formation of oxygen vacancies (VOs). The Ru atoms adjacent to VO are also susceptible to oxidation to soluble ** derivatives, resulting in the collapse of the RuO2 crystal structure, thereby reducing its stability. Therefore, solving this problem is essential to improve the application of RU-based catalysts in PEMWE.
In light of this,The team of Professor Lu Xu of King Abdullah University of Science and Technology (KAUST).An oxygenated anion protection strategy was proposed. The lattice O on the surface of RuO2 is stabilized by using the coordination unsaturated O atom in the oxygenated anion to bond with the coordination unsaturated O atom on the surface of RuO2 to form a saturation site. In this study, density functional theory calculations, electrochemical tests and a series of in-situ spectroscopy experiments were used to screen out the BA-anchored sulfate, which could effectively prevent the loss of RU atoms and improve the stability of the RU-based catalyst in the acidic OER process. In addition, by incorporating W atoms into the RuO2 lattice, the reactivity of the catalyst is further improved. Synthesized BA0 according to theoretical guidance3(so4)δw0.2ru0.5O2 δ catalyst in a three-electrode cell, using 0The 5 M H2SO4 solution was used as the electrolyte and could run stably for 1000 h in a galvanostatic test at 10 mA cm2. The catalyst is assembled at the PEMWE anode and 0When 5 M H2SO4 is used as the electrolyte, it can operate stably for 300 h at a water electrolysis current density of 500 mA cm2. This work provides a new idea for the design of stable and reliable acid OER catalysts.
Figure 1DFT guides the RUO2 stability strategy
aTheoretical calculation of the dissolution of RU atoms in the RUO2(110) crystal plane Gibbs free energy diagram;bruo2(110) crystal plane ball stick model;cBinding energy distribution of various metal elements and sulfate on the RuO2(110) crystal plane;dA ball-and-stick model with sulfate anchored to the RuO2(110) crystal plane.
Figure 2Preparation and characterization of catalysts
aba0.3w0.2ru0.TEM diagram of 5SX;bba0.3(so4)δw0.2ru0.TEM diagram of 5O2 δ;cba0.3w0.2ru0.5sx and ba03(so4)δw0.2ru0.S2P XPS spectra of 5O2 δ;dHaadf Stem Diagram;eEDS Mapping Diagram.
Figure 3OER performance test
aOER polarization curve;btafel plots；cMass activity and area activity;dElectric double-layer capacitance CDL;eOER polarization curves normalized by ECSA;fOER Stability Summary;g0.Stability curve in 5 M H2SO4.
Figure 4Analysis of OER activity mechanism
aGibbs free energy diagram of ruo2;bIn-situ ATR-Seiras spectra of RuO2;cba0.4(so4)δru0.Gibbs free energy diagram of 6o2 δ;dIn-situ ATR-Seiras spectra of (SO4)ΔRUO2 δ;eba0.3(so4)δw0.2ru0.Gibbs free energy diagram of 5o2 δ;fba0.3(so4)δw0.2ru0.In-situ ATR-Seiras spectra of 5O2 δ;
Figure 5Mechanism analysis of catalyst stability
aru k-edge xanes spectra;bba0.3(so4)δw0.2ru0.In-situ Exafs spectra of 5O2 δ;cIn situ Exafs spectra of ruO2;dRU 3D XPS spectra before and after OER test;eIntensity plot of V(OH)S V(OH)W in in-situ ATR-SEIRAS spectra;fPourbaix diagram of the ru element;gba0.3(so4)δw0.2ru0.Theoretical calculation of the dissolution of RU atoms in 5O2 δ Gibbs free energy diagram.
Figure 6PEMWE test
aSchematic diagram of PEMWE;bPEMWE polarization curve;cPemwe Stability Summary;d0.Stability curve of PEMWE in 5 M H2SO4.
Conclusion
This study proposes an oxygenated anion protection mechanism. The research team inhibited the excessive oxidation of lattice O by screening out BA-anchored sulfates. At the same time, the reaction overpotential of the catalyst is reduced by the introduction of W. The combined effect of these two effectively improves the acidic OER stability of RU-based catalysts. This study provides a new perspective and strategy for the design of high-stability catalysts.
ToThanks
This study got to:Beijing University of Chemical TechnologyProfessor Zhuang ZhongbinTsinghua UniversityProfessor Wang Dingsheng, as wellKing Abdullah University of Science and Technology, Cafer TProfessor Y**uzDedicated to helping.
Meet the team
Lu XuProfessorHe received his bachelor's, master's and doctoral degrees in mechanical engineering from the University of Hong Kong, conducted postdoctoral research in the Department of Chemistry at Yale University from 2017 to 2020, and established an independent group at King Abdullah University of Science and Technology (KAUST) in Saudi Arabia in March 2021, focusing on high-voltage carbon dioxide electroreduction. Since the establishment of the team, the original scientific research results have been published in Nature Communications (3 papers), Journal of the American Chemical Society, Angewandte Chemie, Chemical Engineering Journal, and Journal of the Energy Chemistry and other top international journals, and the United States Northwestern University, the University of Toronto, the University of Paris, University College London, Tsinghua University, the University of Pennsylvania, the National University of Singapore and other universities to maintain close scientific research cooperation, and by Saudi Aramco, ACWA Power and other companies funded by the research and development of industrial-grade electrolyzers. The team has been recruiting outstanding doctoral students and postdoctoral fellows for a long time, with excellent salary, complete supporting facilities for scientific research and living in the school, and a laboratory**:lecskaust.edu.sa。Interested parties can send their resumes to [email protected]。
References
yanrong xue, jiwu zhao, liang huang, ying-rui lu, abdul malek, ge gao, zhongbin zhuang, dingsheng wang, cafer t. y**uz, and xu lu* stabilizing ruthenium dioxide with cation-anchored sulfate for durable oxygen evolution in proton-exchange membrane water electrolyzers. nature communications. 2023. doi: .