Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Avenue, Ann Arbor, MI, 48109, USA.
Department of Chemistry and Energy Sciences Institute, Yale University, New Haven, CT, 06520, USA.
Nat Commun. 2023 Jan 12;14(1):179. doi: 10.1038/s41467-023-35782-z.
Seawater electrolysis provides a viable method to produce clean hydrogen fuel. To date, however, the realization of high performance photocathodes for seawater hydrogen evolution reaction has remained challenging. Here, we introduce n-p Si photocathodes with dramatically improved activity and stability for hydrogen evolution reaction in seawater, modified by Pt nanoclusters anchored on GaN nanowires. We find that Pt-Ga sites at the Pt/GaN interface promote the dissociation of water molecules and spilling H* over to neighboring Pt atoms for efficient H production. Pt/GaN/Si photocathodes achieve a current density of -10 mA/cm at 0.15 and 0.39 V vs. RHE and high applied bias photon-to-current efficiency of 1.7% and 7.9% in seawater (pH = 8.2) and phosphate-buffered seawater (pH = 7.4), respectively. We further demonstrate a record-high photocurrent density of ~169 mA/cm under concentrated solar light (9 suns). Moreover, Pt/GaN/Si can continuously produce H even under dark conditions by simply switching the electrical contact. This work provides valuable guidelines to design an efficient, stable, and energy-saving electrode for H generation by seawater splitting.
海水电解提供了一种生产清洁氢气燃料的可行方法。然而，迄今为止，实现用于海水析氢反应的高性能光阴极仍然具有挑战性。在这里，我们介绍了 n-p 硅光阴极，其通过锚定在 GaN 纳米线上的 Pt 纳米团簇修饰，在海水中的析氢反应中具有显著提高的活性和稳定性。我们发现，Pt/GaN 界面处的 Pt-Ga 位促进水分子的解离，并将 H*溢出到相邻的 Pt 原子上，从而实现高效的 H 生产。Pt/GaN/Si 光阴极在海水中（pH=8.2）和磷酸盐缓冲海水中（pH=7.4）分别在 0.15 和 0.39 V 相对于 RHE 时达到-10 mA/cm 的电流密度以及 1.7%和 7.9%的高光电流密度转换效率，在聚光太阳光（9 倍太阳）下，其光电流密度进一步达到了约 169 mA/cm 的记录高位。此外，通过简单地切换电接触，Pt/GaN/Si 甚至可以在黑暗条件下连续产生 H。这项工作为通过海水分解产生 H 提供了有价值的指导，以设计高效、稳定和节能的电极。
