微结构调节的倒金字塔形硅光电阴极用于高效产氢,Nanoscale

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微结构调节的倒金字塔形硅光电阴极用于高效产氢
Nanoscale ( IF 5.8 ) Pub Date : 2022-10-28 , DOI: 10.1039/d2nr04706c
Yumeng Liu _{1,

2} , Shuai Zhao _{1,

2} , Di Zhang _{1,

2} , Zhiqiang Liu _{2,

3} , Guodong Yuan _{1,

2}

Affiliation

具有倒金字塔阵列（SiIP）的黑硅电极由于其优异的光电性能和准亲水性，有望用于高效的光电化学水分解。在这项工作中，详细研究了 SiIP 光电阴极的微观结构调控。我们发现，在侧壁经过铜辅助化学蚀刻（Cu-ACE）处理的SiIPs上，分布着大量的微坑（深孔和浅槽），这些微坑恰好决定了电极的性能，这是同质化的结果。 Si 的Cu ²⁺氧化。此外，SiIP微结构特征可以通过以下方式有效调整控制蚀刻剂成分并引入碱后处理。考虑到光捕获能力和电荷分离能力之间的权衡，我们优化了 SiIP 光电阴极的析氢反应 (HER) 活性，其起始电位相对于 RHE 降低至-0.35 V。在此基础上，我们构建了可靠的异质结以进一步改善缓慢的 HER 动力学。优化的 SiIPs/TiO ₂ /MoS _x阴极表现出相当大的光电流密度 9.45 mA cm ^-2在酸性介质中 HER 过电位为零 18 小时。值得注意的是，我们的工作对 Cu-ACE 中微坑的形成和消除提出了详细的物理见解，并描述了基于 SiIP 的电极性能对微观结构形态的依赖性，为其在无偏整体水分解中的潜在应用铺平了道路。

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Microstructure-regulated inverted pyramidal Si photocathodes for efficient hydrogen generation

Black silicon electrodes with inverted pyramid arrays (SiIPs) are promising for efficient photoelectrochemical water splitting due to their excellent photoelectric properties and quasi-hydrophilicity. In this work, an elaborate study on microstructure regulation of SiIP photocathodes is reported. We find that on SiIPs where sidewalls have been processed with copper-assisted chemical etching (Cu-ACE), there are vast numbers of micro-pits distributed (deep holes and shallow grooves) that exactly determine electrode performance, which is a result of homogeneous Cu²⁺ oxidation of Si. Furthermore, SiIP microstructural features can be effectively adjusted via controlling the etchant composition and introducing alkali post-treatment. Taking the trade-off between light trapping ability and charge separation capacity into consideration, we optimized the hydrogen evolution reaction (HER) activity of a SiIP photocathode, and its onset potential was decreased to −0.35 V vs. RHE. On this basis, we constructed reliable heterojunctions to further improve the sluggish HER kinetics. The optimized SiIPs/TiO₂/MoS_x cathode exhibits a considerable photocurrent density of 9.45 mA cm⁻² at zero HER overpotential for 18 h in acidic media. Notably, our work presents a detailed physical insight into micro-pit formation and elimination in Cu-ACE, and describes the dependency of SiIP-based electrode performance on the microstructure morphology, paving a new way for its potential application in unbiased overall water splitting.

更新日期：2022-10-28

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