【作者】 刘斌；

【导师】 王拓；

【作者基本信息】 天津大学 ， 化学工程与技术， 2021， 博士

【摘要】 化石能源的过度使用造成了能源危机、环境污染等问题。寻求可再生能源代替传统的化石能源被认为是解决上述问题的有效手段。太阳能因其取之不尽、用之不竭的特点,被认为是理想的可再生能源。但太阳能的间歇性、分散性对能源供给的连续性、稳定性带来了挑战。将太阳能转化为稳定的可储存的化学能被认为是未来太阳能高效利用的发展方向。单晶硅材料凭借其丰富的地壳含量、稳定、无毒以及成本相对较低的优势,在太阳能电池领域大放异彩,并占据了超过90%的市场份额。而同样以单晶硅材料制备的光电极,在人工光合成过程,如水分解制氢气与二氧化碳还原至高附加值产物中所展现出的活性与稳定性均不尽如人意,这大大限制了单晶硅光电极的发展。究其原因,单晶硅光电极表面催化剂对太阳光的寄生吸收以及单晶硅光电极表界面处高密度的缺陷态是主要原因。本论文针对传统单晶硅光电极中催化剂与太阳光无法解耦的矛盾,提出并构建了背面光照的光电极结构,基于非晶硅薄膜的化学钝化作用,大幅降低了少数载流子在单晶硅表面的复合速率,提升了少数载流子的传输距离,揭示了光生电荷在硅电极表面的复合规律,实现了催化剂与太阳光的空间解耦,获得了单晶硅光电极中最高的太阳能到化学能转化效率。针对单晶硅光电极光生电荷传输距离与表面钝化效果难以兼顾的矛盾,本论文提出了“双面钝化”的表界面修饰策略,借助非晶硅薄膜的化学钝化作用修复单晶硅表面的缺陷态,同时引入非晶二氧化钛薄膜作为第二钝化层,钝化由金属诱导产生的缺陷态。因此,在双面钝化层的单晶硅光电极界面处构建了高效、无损的电荷传输通道,明确了光生电荷在硅电极表界面处的传输机制,获得了优异的水分解制氢、产氧性能,实现了同类光电极中最高的太阳能到化学转化效率。本论文基于背面光照的单晶硅光电极,开发了太阳光驱动的二氧化碳还原系统,实现了流动电解池与单晶硅光电极的耦合,借助单晶硅光电极产生的光电压降低二氧化碳还原体系的总反应电压,提升了太阳能到化学能的转化效率,拓展了单晶硅材料的应用范围,证明了单晶硅光电极在流动电解池中应用的可能性,推动了硅电极在人工光合成中的发展。更多还原

【Abstract】 With the reduction of fossil fuels and the aggravation of greenhouse effect,the access to clean,affordable and reliable energy is becoming a cornerstone of the world’s increasing prosperity and economic growth.The inexhaustible solar energy is a promising energy available on the earth,but its decentralized and intermittent nature remains a great challenge for our energy demands.The conversion of light into value added fuels that could be stored or transported is an effective route.Photoelectrocatalytic reactions based on semiconductor photoelectrode represent an effective approach for the future use of solar energy.Si is an attractive candidate owing to its narrow band gap.It is expected that Si will remain the dominant material for semiconductor and photovoltaic applications in the foreseeable future due to its low cost,abundance,and non-toxicity.However,Si photoelectrodes presented unsatisfactory performance and stability due to the parasitic light absorption of cocatalyst and recombination of minority carriers at the Si photoelectrodes surface.This dissertation proposes a Si photoelectrode with an ultra-long minority carrier diffusion length passivated by an amorphous Si layer,which provides a chemically passivated surface.With this extremely long carrier diffusion length,it is possible to separate the catalyst layer（metal）with the light absorption region on different sides of the Si photoelectrode,forming a double-side Si photoelectrode for photoelectrochemical water reduction and oxidation.To eliminate the defects at the Si photoelectrode surface,this dissertation designs and realizes a bifacial passivation strategy for the metal/Si interface of the Si photoelectrode,featuring a bi-layer stack consisting of amorphous silicon（a-Si）for passivating the silicon surface and a metal oxide（Ti O₂）for passivating the metal surface.Upon the bifacial passivation of both a-Si and Ti O₂,the minority carrier lifetime of the Si photoanode was significantly improved.Enabled by this extremely long minority carrier lifetime,it becomes possible to place the Si junction on the back side of a Si substrate to construct an inverted structure to eliminate the parasitic light absorption of traditional Si photoelectrodes.This dissertation proposes a Si photoelectrode promoted CO₂ reduction reaction system in the flow cell for the first time.The photovoltage generated by the Si photoelectrode was designed to compensate the external energy input,the electricity utilization efficiency was promoted significantly after introducing Si photoelectrode in CRR.更多还原