Sayed Suzan Abdelfattah, Arunachalam Maheswari, Badiger Jyoti, Kanase Rohini Subhash, Ha Jun-Seok, Ahn Kwang-Soon, Kang Soon Hyung
Department of Chemicals and Engineering, Chonnam National University, Gwangju 61186, Republic of Korea.
Department of Chemistry Education and Optoelectronic Convergence Research Center, Chonnam National University, Gwangju 61186, Republic of Korea.
ACS Appl Mater Interfaces. 2024 Nov 20;16(46):63427-63439. doi: 10.1021/acsami.4c10560. Epub 2024 Nov 6.
Photoelectrochemical water splitting, which uses sunlight to produce clean hydrogen fuel, is gaining traction with rising concerns about fossil fuels and pollution. Silicon (Si) photocathodes are promising for this process due to their light absorption and favorable band alignment for hydrogen production. However, limitations such as reflectance, low photovoltage, and rapid photocorrosion hinder their overall performance and stability. An interfacial insulating layer such as SiO ensures superior durability to -Si photocathodes. However, the inherent heterogeneity and intrinsic defects pose challenges to effective surface passivation. This study investigates the challenges of photocorrosion and utilization of a thin titanium nitride (TiN) passivation layer deposited using direct-current magnetron sputtering to protect the native silicon oxide (SiO) layer. Additionally, a molybdenum oxynitride (Mo(O,N)) bifunctional layer is employed to enhance both the electrocatalytic activity and durability of the photocathode. The presence of oxygen and nitrogen within this cocatalyst layer modifies the surface chemistry of the -Si photocathode, promoting favorable interfacial interactions with electrolyte species during PEC reactions. This modification facilitates efficient charge transfer processes and accelerates reaction kinetics, ultimately optimizing the performance and operational lifetime of the photocathode. The resulting Mo(O,N)/TiN/-Si photocathode exhibited a remarkable onset potential of +0.46 V in harsh acidic conditions under simulated sunlight (AM 1.5G illumination, 100 mW·cm). Notably, the photocathode demonstrated exceptional long-term stability exceeding 140 h, highlighting the combined TiN passivation and Mo(O,N) cocatalyst as a protection strategy.
光电化学水分解利用阳光生产清洁的氢燃料，随着人们对化石燃料和污染问题的日益关注，这种技术越来越受到关注。硅（Si）光阴极因其光吸收特性以及对产氢有利的能带排列，在这个过程中具有很大潜力。然而，诸如反射率、低光电压和快速光腐蚀等限制因素阻碍了它们的整体性能和稳定性。诸如SiO之类的界面绝缘层可确保 -Si光阴极具有卓越的耐久性。然而，其固有的不均匀性和内在缺陷给有效的表面钝化带来了挑战。本研究调查了光腐蚀的挑战以及利用直流磁控溅射沉积的薄氮化钛（TiN）钝化层来保护原生氧化硅（SiO）层的情况。此外，采用氮氧化钼（Mo(O,N)）双功能层来增强光阴极的电催化活性和耐久性。这种助催化剂层中氧和氮的存在改变了 -Si光阴极的表面化学性质，在光电化学（PEC）反应期间促进了与电解质物种的良好界面相互作用。这种改性促进了有效的电荷转移过程并加速了反应动力学，最终优化了光阴极的性能和使用寿命。所得的Mo(O,N)/TiN/-Si光阴极在模拟阳光（AM 1.5G光照，100 mW·cm）下的苛刻酸性条件下表现出显著的起始电位为 +0.46 V。值得注意的是，该光阴极表现出超过140小时的出色长期稳定性，突出了TiN钝化和Mo(O,N)助催化剂相结合作为一种保护策略的效果。
