It is crucial to efficiently separate and transport photo-induced charge carriers for the effective implementation of photocatalysis toward environmental remediation. A rational design strategy is proposed to validate such proposition through the construction of an interfacial structure in the form of LDH/Zn₂SnO₄ heterostructures in this research. The interfacial charge transfer on LDH/Zn₂SnO₄ is greatly promoted via the unique charge transfer pathway, as characterized by transient photocurrent responses, X-ray photoelectron spectroscopy, electron paramagnetic resonance spectrum, and photoluminescence analysis. As such, it contributes to the generation of reactive oxygen species (ROS) and the activation of reactants for the mineralization of toluene. According to the in situ DRIFTS spectra analysis, the accumulation of benzoic acid takes place possibly through the partial oxidation of the methyl group on toluene at the interface of the LDH/Zn₂SnO₄ heterostructure. This process can greatly promote the photocatalytic oxidation of toluene with the enhanced ring-opening efficiency. The LDH/Zn₂SnO₄ is thus demonstrated as superior photocatalyst against toluene (removal efficiency of 89.5%; mineralization of 83.1%; and quantum efficiency of 4.55 × 10⁻⁶ molecules/photon). As such, the performance of this composite far exceeds that of their individual components (e.g., P25, pure Mg-Al LDH, or Zn₂SnO₄). This study is expected to offer a new path to the interfacial charge transfer mechanism based on the design of highly efficient photocatalysts for air purification.

The rapid rise of modern industry is the source of unchecked effluents containing many pernicious heavy metals (e.g., cadmium). To rehabilitate the ecology, food resources, and health of humans and animals, various conventional methodologies are being used in wastewater treatment facilities for the abatement of cadmium. Nonetheless, the development of advanced, economical, and efficient adsorbents is needed because of the many shortcomings of conventional methods (e.g., high cost, intensive operation, and inefficiency). Recent advancements in materials science and chemistry have introduced the use of nanomaterials, which possess very high specific surface areas and multiple functionalities, for the removal of specific targets such as cadmium. This review explores the recent developments and trends in nanomaterial adsorption technology for the mitigation of cadmium. The paper further surveys the present obstacles and future opportunities for the advancement of nanomaterial-based technologies in the area of water treatment.

Discharging dye contaminants into water is a major concern around the world. Among a variety of methods to treat dye-contaminated water, photocatalytic degradation has gained attention as a tool for treating the colored water. Herein, we review the recent advancements in photocatalysis for dye degradation in industrial effluents by categorizing photocatalyst materials into three generations. First generation photocatalysts are composed of single-component materials (e.g., TiO₂, ZnO, and CdS), while second generation photocatalysts are composed of multiple components in a suspension (e.g., WO₃/NiWO₄, BiOI/ZnTiO₃, and C₃N₄/Ag₃VO₄). Photocatalysts immobilized on solid substrates are regarded as third generation materials (e.g., FTO/WO₃-ZnO, Steel/TiO₂-WO₃, and Glass/P-TiO₂). Photocatalytic degradation mechanisms, factors affecting the dye degradation, and the lesser-debated uncertainties related to the photocatalysis are also discussed to offer better insights into environmental applications. Furthermore, quantum yields of different photocatalysts are calculated, and a performance evaluation method is proposed to compare photocatalyst systems for dye degradation. Finally, we discuss the present limitations of photocatalytic dye degradation for field applications and the future of the technology.

Despite the improvement in sensing technologies, detection of small and highly reactive molecules like formaldehyde remains a highly challenging area of research. Applications of nanomaterials/nanostructures and their composites have increased as effective sensing platforms (e.g., reaction time, sensitivity, and selectivity) for the detection of aqueous or gaseous formaldehyde based on diverse sensing principles. In this review, the basic aspects of important nanomaterial-based sensing systems (e.g., electrochemical, electrical, biological, and mass variation sensors) were evaluated in relation to performance, cost, and practicality of sensing gas phase formaldehyde. Accordingly, existing knowledge gaps in such applications were assessed in various respects along with suitable recommendations for building a new roadmap for the expansion of chemical sensing technology of gas phase formaldehyde.

Advances in metal-organic frameworks (MOFs) resulted in significant contributions to diverse applications such as carbon capture, gas storage, heat transformation and separation along with emerging applications toward catalysis, medical imaging, drug delivery, and sensing. The unique in situ and ex situ structural features of MOFs can be tailored by conceptual selection of the organic (e.g., ligand) and inorganic (e.g., metal) components. Here, we provide a comprehensive review on the synthesis and characterization of MOFs, particularly with respect to controlling their size and morphology. A better understanding of the specific size and morphological parameters of MOFs will help initiate a new era for their real-world applications. Most importantly, this assessment will help develop novel synthesis methods for MOFs and their hybrid/porous materials counterparts with considerably improved properties in targeted applications.

Over the past few decades, coordination polymers/metal organic frameworks (CPs/MOFs) have drawn a great deal of attention for diverse applications due to their advantages of intrinsically tunable chemical structure, flexible architecture, high pore volume, high surface area, multifunctional properties, etc. To date, numerous CPs/MOFs have been developed and employed for the treatment and control of gaseous pollutants, such as volatile organic compounds (VOCs), through capture, sorptive removal, and catalytic degradation. Nevertheless, there are also some key drawbacks and challenges for the practical application of these systems (e.g., poor selectivity, high energy (and fiscal) cost, high synthesis cost, low capacity, and difficulties in regeneration and recycling). In this review, recent developments in CPs/MOFs research are described with their associated mechanisms for capture, sorptive removal, and catalytic degradation of VOCs. To this end, we discuss the key variables and challenges for afforded abatement of VOCs through CPs/MOFs technologies. Hopefully, this review will help the scientific community set future directions for the advancement of CPs/MOFs techniques for the effective management of diverse environmental issues.