Hajibabaei Hamed, Little Daniel J, Pandey Ayush, Wang Dunwei, Mi Zetian, Hamann Thomas W
Department of Chemistry , Michigan State University , 578 S Shaw Lane , East Lansing , Michigan 48824-1322 , United States.
Department of Electrical Engineering and Computer Science , University of Michigan , 1301 Beal Avenue , Ann Arbor , Michigan 48109 , United States.
ACS Appl Mater Interfaces. 2019 May 1;11(17):15457-15466. doi: 10.1021/acsami.8b21194. Epub 2019 Apr 22.
Tantalum nitride is a promising photoanode material for solar water splitting, but further study and practical use are constrained by the harsh conditions of the synthesis from Ta metal. Here, we report the direct deposition of crystalline TaN on fluorine-doped tin oxide (FTO) substrate via a custom-built atomic layer deposition (ALD) system. A combination of TaCl (Ta precursor) and ammonia (N source) was sequentially pulsed into the ALD reactor with the substrate heated to 550 °C to deposit compact and thin films of TaN with controllable thicknesses on FTO substrates. Importantly, it is shown that the FTO is chemically and structurally stable under the reducing conditions of ammonia at 550 °C. These electrodes produced an exceptional photocurrent onset potential of ∼0.3 V versus reversible hydrogen electrode (RHE) with a maximum photocurrent of ∼2.4 mA cm at 1.23 V versus RHE. Results of photoelectrochemical investigations as a function of film thickness and illumination direction reveal that the performance of TaN is controlled by a hole diffusion length of ∼50 nm. These results are crucial for the successful integration of TaN in efficient unassisted water-splitting applications.
氮化钽是一种很有前景的用于太阳能水分解的光阳极材料，但由于从金属钽合成时条件苛刻，其进一步研究和实际应用受到限制。在此，我们报道了通过定制的原子层沉积（ALD）系统在氟掺杂氧化锡（FTO）衬底上直接沉积结晶氮化钽。将TaCl（钽前驱体）和氨（氮源）依次脉冲注入ALD反应器中，同时将衬底加热到550°C，以便在FTO衬底上沉积致密且厚度可控的氮化钽薄膜。重要的是，研究表明FTO在550°C氨的还原条件下化学和结构稳定。相对于可逆氢电极（RHE），这些电极产生了约0.3 V的异常光电流起始电位，在相对于RHE为1.23 V时最大光电流约为2.4 mA cm²。作为薄膜厚度和光照方向函数的光电化学研究结果表明，氮化钽的性能受约50 nm的空穴扩散长度控制。这些结果对于氮化钽成功集成到高效无辅助水分解应用中至关重要。
