双电极电解法合成高效WO_(3-x)/石墨烯析氧反应光电催化剂

Electrosynthesis of Highly Efficient WO_(3−x)/Graphene(Photo-)Electro-Catalyst by Two-Electrode Electrolysis System for Oxygen Evolution Reaction

将非贵金属氧化物与石墨烯复合在一起可以构建高活性的析氧反应电催化剂.为了减少传统合成方法的复杂性,本文设计了一种简便的电化学合成方法制备高效的WO_(3-x)/石墨烯光电催化剂,通过双电极电解体系,将阴极的石墨剥离成石墨烯,钨丝阳极在还原性电解质溶液中部分转化为富含氧空穴的WO_(3-x).在所有合成的样品中,WO_(3-x)/G-2表现出最佳的电催化析氧性能,在10 mA/cm^(2)时过电位为320 mV(无iR补偿),优于商RuO_(2)(341 mV).随着光照的引入,WO_(3-x)/G-2的活性大大增强,其过电位降低至290mV,这主要受益于光电流效应产生的额外反应路径和光生载流子(h^(+))产生的额外活性位点.表征结果表明,富含氧空穴的WO_(3-x)和石墨烯都有助于提高析氧性能.WO_(3-x)对析氧反应的活性影响由氧空穴浓度与粒径的协同作用决定.石墨烯不仅能够分散WO_(3-x)纳米颗粒,而且能提高材料整体导电性,促进电子传输.该工作为设计高效析氧反应WO_(3-x)/石墨烯光电催化复合材料提供了一种新思路和方法.

Integration of non-noble transition metal oxides with graphene is known to construct high-activity electrocatalysts for oxygen evolution reduction(OER).In order to avoid the complexity of traditional synthesis process,a facile electrochemical method is elaborately designed to engineer efficient WO_(3−x)/graphene(photo-)electrocatalyst for OER by a two-electrode electrolysis system,where graphite cathode is exfoliated into graphene and tungsten wire anode evolves into VO-rich WO_(3−x)profiting from formed reductive electrolyte solution.Among as-prepared samples,WO_(3−x)/G-2 shows the best electrocatalytic performance for OER with an overpotential of 320 mV(without iR compensation)at 10 mA/cm^(2),superior to commercial RuO_(2)(341 mV).With introduction of light illumination,the activity of WO_(3−x)/G-2 is greatly enhanced and its overpotential decreases to 290 mV,benefiting from additional reaction path produced by photocurrent effect and extra active sites generated by photogenerated carriers(h^(+)).Characterization results indicate that both VO-rich WO_(3−x)and graphene contribute to the efficient OER performance.The activity of WO_(3−x)for OER is decided by the synergistic effect between VO concentration and particle size.The graphene could not only disperse WO_(3−x)nanoparticles,but also improve the holistic conductivity and promote electron transmission.This work supports a novel method for engineering WO_(3−x)/graphene composite for highly efficient(photo-)electrocatalytic performance for OER.