Graduate School of Green Energy Engineering, Hoseo University , Asan 336-795, Korea.
Department of Chemistry, Korea University , Jochiwon 339-700, Korea.
ACS Appl Mater Interfaces. 2017 Oct 25;9(42):36715-36722. doi: 10.1021/acsami.7b09040. Epub 2017 Oct 12.
Photocatalysts for water splitting are the core of renewable energy technologies, such as hydrogen fuel cells. The development of photoelectrode materials with high efficiency and low corrosivity has great challenges. In this study, we report new strategy to improve performance of tantalum nitride (TaN) nanocrystals as promising photoanode materials for visible-light-driven photoelectrochemical (PEC) water splitting cells. The surface of TaN nanocrystals was modified with boron whose content was controlled, with up to 30% substitution of Ta. X-ray photoelectron spectroscopy revealed that boron was mainly incorporated into the surface oxide layers of the TaN nanocrystals. The surface modification with boron increases significantly the solar energy conversion efficiency of the water-splitting PEC cells by shifting the onset potential cathodically and increasing the photocurrents. It reduces the interfacial charge-transfer resistance and increases the electrical conductivity, which could cause the higher photocurrents at lower potential. The onset potential shift of the PEC cell with the boron incorporation can be attributed to the negative shift of the flat band potential. We suggest that the boron-modified surface acts as a protection layer for the TaN nanocrystals, by catalyzing effectively the water splitting reaction.
用于水分解的光催化剂是可再生能源技术（如氢燃料电池）的核心。开发高效、低腐蚀性的光电电极材料具有很大的挑战。在这项研究中，我们报告了一种新策略，可提高氮化钽 (TaN) 纳米晶体作为可见光驱动光电化学 (PEC) 水分解电池有前途的光阳极材料的性能。TaN 纳米晶体的表面用硼进行了改性，其含量得到了控制，最高可取代 Ta 的 30%。X 射线光电子能谱表明，硼主要掺入 TaN 纳米晶体的表面氧化物层中。硼的表面修饰显著提高了水分解 PEC 电池的太阳能转换效率，通过将起始电位阴极化并增加光电流来实现。它降低了界面电荷转移电阻并增加了电导率，这可能导致在较低电位下产生更高的光电流。PEC 电池中硼掺入引起的起始电位偏移可归因于平带电位的负移。我们认为，硼修饰的表面可以作为 TaN 纳米晶体的保护层，通过有效催化水分解反应。
