Preparation of Calcium-Doped Y<sub>2</sub>Ru<sub>2</sub>O<sub>7</sub> Pyrochlore Oxide and Its Electrocatalytic Hydrogen Precipitation Properties

本研究合成了烧绿石氧化物Y2Ru2O7 (YRO)和Ca掺杂的Y1.7Ca0.3Ru2O7 (YCRO)材料，系统研究了它们在碱性介质中的电催化析氢性能(HER)，并与商业Pt/C和RuO2催化剂进行了对比。结果表明，Ca掺杂显著提高了催化活性，使达到10 mA∙cm−2电流密度所需过电位从162 mV大幅降低至81 mV，塔菲尔斜率从91.8降至63.8 mV∙dec−1，接近商业Pt/C催化剂(52 mV, 54.0 mV∙dec−1)。YCRO还表现出优异的稳定性，在2000次循环伏安循环和20小时连续电解后活性几乎无衰减。通过多种表征手段(XRD、XPS、SEM和TEM等)，揭示了Ca掺杂增强HER性能的电催化机理机制，Ca2+部分替代Y3+，导致Ru的d-band中心下移(靠近费米能级)，优化了氢吸附能；提高了氧空位浓度和表面亲水性，改善了水分子吸附和活化。研究为开发高效金属氧化物析氢电催化剂提供了新思路和理论依据。In this thesis, pyrochlore oxide Y2Ru2O7 (YRO) and Ca-doped Y1.7Ca0.3Ru2O7 (YCRO) materials have been synthesized, and their electrocatalytic hydrogen-removal performance (HER) in alkaline media has been systematically investigated and compared with commercial Pt/C and RuO2 catalysts. The results showed that Ca doping significantly improved the catalytic activity, resulting in a significant reduction of the overpotential required to reach a current density of 10 mA∙cm−2 from 162 mV to 81 mV, and a reduction of the Tafel slope from 91.8 to 63.8 mV∙dec−1, which is close to that of commercial Pt/C catalysts (52 mV, 54.0 mV∙dec−1). YCRO also exhibits excellent stability, with virtually no decay in activity after 2000 cyclic voltammetry cycles and 20 hours of continuous electrolysis. The electrocatalytic mechanism of Ca doping to enhance HER performance was revealed by various characterization means (XRD, XPS, SEM and TEM, etc.), where Ca2+ partially replaces Y3+, leading to a downward shift of the d-band center of Ru (close to the Fermi energy level) and optimizing the hydrogen adsorption energy; and an increase in the concentration of the oxygen vacancies and the hydrophilicity of the surface, which improves the adsorption and activation of water molecules. The study provides new ideas and theoretical basis for the development of efficient metal oxide hydrogen precipitation electrocatalysts.