Ren Kexin, Zhou Jiayi, Wu Zihao, Sun Qi, Qi Limin
Beijing National Laboratory for Molecular Science (BNLMS), College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China.
Small. 2024 Jan;20(1):e2304835. doi: 10.1002/smll.202304835. Epub 2023 Aug 31.
Photoelectrochemical (PEC) water splitting represents an attractive strategy to realize the conversion from solar energy to hydrogen energy, but severe charge recombination in photoanodes significantly limits the conversion efficiency. Herein, a unique BiVO (BVO) nanobowl (NB) heterojunction photoanode, which consists of [001]-oriented BiOCl underlayer and BVO nanobowls containing embedded BiOCl nanocrystals, is fabricated by nanosphere lithography followed by in situ transformation. Experimental characterizations and theoretical simulation prove that nanobowl morphology can effectively enhance light absorption while reducing carrier diffusion path. Density functional theory (DFT) calculations show the tendency of electron transfer from BVO to BiOCl. The [001]-oriented BiOCl underlayer forms a compact type II heterojunction with the BVO, favoring electron transfer from BVO through BiOCl to the substrate. Furthermore, the embedded BiOCl nanoparticles form a bulk heterojunction to facilitate bulk electron transfer. Consequently, the dual heterojunctions engineered BVO/BiOCl NB photoanode exhibits attractive PEC performance toward water oxidation with an excellent bulk charge separation efficiency of 95.5%, and a remarkable photocurrent density of 3.38 mA cm at 1.23 V versus reversible hydrogen electrode, a fourfold enhancement compared to the flat BVO counterpart. This work highlights the great potential of integrating dual heterojunctions engineering and morphology engineering in fabricating high-performance photoelectrodes toward efficient solar conversion.
光电化学（PEC）水分解是实现太阳能向氢能转化的一种有吸引力的策略，但光阳极中严重的电荷复合显著限制了转化效率。在此，通过纳米球光刻法随后进行原位转化制备了一种独特的BiVO（BVO）纳米碗（NB）异质结光阳极，它由[001]取向的BiOCl底层和包含嵌入BiOCl纳米晶体的BVO纳米碗组成。实验表征和理论模拟证明，纳米碗形态可以有效增强光吸收，同时减少载流子扩散路径。密度泛函理论（DFT）计算表明了电子从BVO转移到BiOCl的趋势。[001]取向的BiOCl底层与BVO形成紧密的II型异质结，有利于电子从BVO通过BiOCl转移到基底。此外，嵌入的BiOCl纳米颗粒形成体相异质结以促进体相电子转移。因此，通过双异质结工程设计的BVO/BiOCl NB光阳极在水氧化方面表现出有吸引力的PEC性能，具有95.5%的优异体电荷分离效率，在相对于可逆氢电极1.23 V时具有3.38 mA cm的显著光电流密度，与平面BVO对应物相比提高了四倍。这项工作突出了在制造用于高效太阳能转化的高性能光电极中整合双异质结工程和形态工程的巨大潜力。
