Ghosh Koushik, Roy Sanjoy Sur, Giri P K
Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039, India.
Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati 781039, India.
ACS Appl Mater Interfaces. 2024 Aug 14;16(32):42007-42020. doi: 10.1021/acsami.4c04167. Epub 2024 Aug 1.
The distinctive properties of 2D MXenes have garnered significant interest across various fields, including wastewater treatment and photo/electro-catalysis. The integration of inexpensive semiconductor nanostructures with 2D MXenes offers a promising strategy for applications such as wastewater treatment and photoelectrochemical hydrogen production. In this study, we employed an in situ hydrothermal method to immobilize 1D BiS nanorods and self-reduced metallic bismuth nanoparticles (Bi NPs) onto TiCT MXene nanosheets, resulting in the formation of a Bi/BiS/TiCT (0/1D/2D) composite catalyst, which demonstrates an outstanding efficacy in both the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) and photoelectrochemical hydrogen production. Remarkably, a 4-NP reduction efficiency of 100% was achieved only in 4 min with a reduction rate of 1.14 min, which is outstanding, and it is ∼3.8 times faster than pristine BiS nanorods (0.3 min). Furthermore, the photoelectrochemical assessment reveals that the Bi/BiS/TiCT catalyst displays remarkable hydrogen evolution reaction (HER) efficiency in an alkaline electrolyte. It exhibits a significantly lower overpotential and Tafel slope of 73 mV and 84 mV/dec, respectively, compared to pristine BiS nanorods, which are found to be 129 mV and 145 mV/dec under light illumination. The superior reduction performance of 4-NP and charge transfer mechanism is further investigated through density functional theory (DFT) calculations, alongside validation using various microscopic and spectroscopic techniques. Interestingly, the DFT analysis revealed modifications in the partial density of states of BiS within the band gap region due to the successful anchoring of TiCT nanosheets and metallic Bi NPs, facilitating efficient charge transport and separation across the local junctions. Ultraviolet photoelectron spectroscopy provided insights into band alignment and interfacial charge transfer across the Bi/BiS/TiCT junction on a microscopic scale. This work is significant for the development of MXene-based hybrid catalysts, and it provides a deeper understanding of the reduction mechanism of organic pollutants and superior charge transport in the hybrid system for photoelectrochemical hydrogen production.
二维MXenes的独特性质在包括废水处理和光/电催化在内的各个领域引起了极大的关注。将廉价的半导体纳米结构与二维MXenes相结合，为废水处理和光电化学制氢等应用提供了一种有前景的策略。在本研究中，我们采用原位水热法将一维BiS纳米棒和自还原的金属铋纳米颗粒（Bi NPs）固定在TiCT MXene纳米片上，从而形成了Bi/BiS/TiCT（0/1D/2D）复合催化剂，该催化剂在将4-硝基苯酚（4-NP）还原为4-氨基苯酚（4-AP）以及光电化学制氢方面均表现出出色的效果。值得注意的是，仅在4分钟内就实现了100%的4-NP还原效率，还原速率为1.14分钟，这非常出色，并且比原始BiS纳米棒（0.3分钟）快约3.8倍。此外，光电化学评估表明，Bi/BiS/TiCT催化剂在碱性电解质中表现出显著的析氢反应（HER）效率。与原始BiS纳米棒相比，其过电位和塔菲尔斜率分别显著降低，为73 mV和84 mV/dec，而在光照下原始BiS纳米棒的过电位和塔菲尔斜率分别为129 mV和145 mV/dec。通过密度泛函理论（DFT）计算，并结合使用各种显微镜和光谱技术进行验证，进一步研究了4-NP的优异还原性能和电荷转移机制。有趣的是，DFT分析表明，由于TiCT纳米片和金属Bi NPs的成功锚定，BiS在带隙区域的部分态密度发生了变化，这有利于在局部结处实现有效的电荷传输和分离。紫外光电子能谱在微观尺度上提供了关于Bi/BiS/TiCT结处能带排列和界面电荷转移的见解。这项工作对于基于MXene的混合催化剂的开发具有重要意义，并且它为有机污染物的还原机制以及光电化学制氢混合系统中的优异电荷传输提供了更深入的理解。
