钠离子掺杂铋酸铜光阴极的制备及其光电催化性能的研究

Preparation of Sodium Ion Doped Copper Bismuth Oxide Photocathode and Its Photoelectrocatalytic Performance

金属氧化物光电极被认为在未来太阳能制氢方面具有广阔的前景,但由于其固有的载流子迁移率较低而面临着巨大挑战。铋酸铜(CuBi_(2)O_(4))光电阴极在光电化学水分解中具有很大的潜力和应用价值,是未来理想的光电阴极材料之一,本文采用喷雾热解法制备CuBi_(2)O_(4)光电阴极,并通过形貌与能级调控实现了光电性能的突破。首先,通过在CuBi_(2)O_(4)光电阴极中进行Na+掺杂,低价态的Na+取代Bi^(3+)位点形成空穴中心,提升了载流子的迁移能力。与此同时,Na+元素的引入使所制备的CuBi_(2)O_(4)光电阴极具有多孔的纳米形貌,有效地缩短了光生载流子至表面的传输距离。其次,通过对Na+掺杂CuBi_(2)O_(4)光电阴极进行氧气煅烧(Na-CuBi_(2)O_(4)-O2),形成金属空位充当电子受体,减少了Na+掺杂引入的氧空位,从而提高空穴密度,进一步增强了电荷分离效率。这种策略使Na-CuBi_(2)O_(4)-O2光电阴极在0.6V vs.RHE时的光电流密度高达-2.83 mA·cm^(-2),是未经处理的CuBi_(2)O_(4)光电阴极的15倍(-0.18 mA cm^(-2))。结合时间分辨荧光光谱、开尔文探针力显微镜与光电化学研究,揭示了Na-CuBi_(2)O_(4)-O2光电阴极具有更高的载流子寿命与更高的表面光电压。这项工作利用元素掺杂与金属空位增强了CuBi_(2)O_(4)光电阴极的电荷分离和传输能力,实现了其光电性能的较大提升,对未来高性能光电阴极的制备具有指导意义。

Ternary oxide,as a class of photoelectrode materials,are considered promising for solar energy conversion.Copper bismuthate(CuBi_(2)O_(4))photocathode is one of the ideal photocathode materials with great potential and application value in photoelectrochemical water splitting,however,its development and application still face great challenges due to its inherent problem of slow carrier mobility.In this study,CuBi_(2)O_(4) photocathode was prepared by spray pyrolysis and the breakthrough of photoelectrochemical performance was realized by morphology modulation and defect regulation.Firstly,by doping Na+into the CuBi_(2)O_(4) photocathode(Na-CuBi_(2)O_(4)),the Bi^(3+)sites is replaced by the low-valence Na+and hole centers are formed,thus enhancing the carrier transmission capacity.Meanwhile,the introduction of Na+led to a porous nanomorphology of the prepared CuBi_(2)O_(4) photocathode,which effectively shortened the transmission distance of photogenerated carriers to the surface.Secondly,by annealing Na-CuBi_(2)O_(4) in oxygen atmosphere(Na-CuBi_(2)O_(4)-O2),the Na-CuBi_(2)O_(4)-O2 photoelectrode forms multiple metal vacancies as electron acceptors,which reduces the oxygen vacancies brought by Na+doping,thus increasing the hole density and further improving the charge separation efficiency.This strategy resulted in a high photocurrent density of–2.83 mA·cm^(-2) at 0.6 V vs.RHE for the Na-CuBi_(2)O_(4)-O2 photoelectrode, which is 15 times higher than that of the untreated CuBi_(2)O_(4) photoelectrode (–0.18 mA cm^(-2)). Bycombining time-resolved fluorescence spectroscopy, Kelvin probe force microscopy and photoelectrochemicalstudies, it was revealed that the Na-CuBi_(2)O_(4)-O2 photoelectrode exhibits longer carrier lifetime and higher surfacephotovoltage. In a word, this work utilizes elemental doping and metal vacancies to enhance the charge separationand transfer ability of CuBi_(2)O_(4) photocathode, realizing a significant improvement in its photoelectrochemicalperformance, which is of guiding significance for the future development of high-performance photocathodes.