Dual Use of Copper-Modified TiO2 Nanotube Arrays as Material for Photocatalytic NH3 Degradation and Relative Humidity Sensing

Semiconductor photocatalysts: A critical review highlighting the various strategies to boost the photocatalytic performances for diverse applications

The photocatalytic technology illustrates an eco-friendly and sustainable route to overcome environmental and energy issues. The successful construction of a photocatalyst depends on four key elements: light absorption ability, the density of active sites, redox capacity, and photoinduced electron-hole recombination rate. Sincemost of intrinsic semiconductor photocatalysts cannot meet all these requirements, they are often modified to boost their photocatalytic properties. Many strategies have been adopted to design novel and efficient photocatalysts for diverse applications. Herein, we review the most efficient of these strategies and methods focused on effectively overcoming the efficiency limitations of photocatalysts to promote their large-scale application. Subsequently, a particular aim is put on the most current studies for photocatalytic applications, including CO₂ reduction, N₂ fixation, H₂ evolution, and pollutants degradation. Finally, key challenges and future perspectives in designing and implementing semiconductor photocatalysts for large-scale applications are discussed. Therefore, it is foreseen that this review will work as a guide for future research and provides a variety of strategies to develop novel and high-performance photocatalysts for various applications.

Al2O3-Based Hollow Fiber Membranes Functionalized by Nitrogen-Doped Titanium Dioxide for Photocatalytic Degradation of Ammonia Gas

In recent years, reactive ammonia (NH₃) has emerged as a major source of indoor air pollution. In this study, Al₂O₃-based hollow fiber membranes functionalized with nitrogen-doped titanium dioxide were produced and successfully applied for efficient heterogeneous photocatalytic NH₃ gas degradation. Al₂O₃ hollow fiber membranes were prepared using the phase inversion process. A dip-coating technique was used to deposit titanium dioxide (TiO₂) and nitrogen-doped titanium dioxide (N-TiO₂) thin films on well-cleaned Al₂O₃-based hollow fiber membranes. All heterogeneous photocatalytic degradation tests of NH₃ gas were performed with both UV and visible light irradiation at room temperature. The nitrogen doping effects on the NH₃ heterogeneous photocatalytic degradation capacity of TiO₂ were investigated, and the effect of the number of membranes (30, 36, 42, and 48 membranes) of the prototype lab-scale photocatalytic membrane reactor, with a modular design, on the performances in different light conditions was also elucidated. Moreover, under ultraviolet and visible light, the initial concentration of gaseous NH₃ was reduced to zero after only fifteen minutes in a prototype lab-scale stage with a photocatalytic membrane reactor based on an N-TiO₂ photocatalyst. The number of Al₂O₃-based hollow fiber membranes functionalized with N-TiO₂ photocatalysts increases the capacity for NH₃ heterogeneous photocatalytic degradation.