Smart Nanomaterials for Photo-Catalytic Applications

Introduction

Smart materials are a type of material that may have one or more properties changed simply by changing the external environment. Such changes in material characteristics enable the creation of so-called responsive materials, which have a significant impact on the rapid advancement of materials science, water treatment, and energy generation applications. The ability of smart materials to adjust to external environmental changes such as temperature, pH, light, moisture, and fluid composition in order to activate their unique functionalities is one of their most remarkable qualities (Wieszczycka et al., 2021; Yoshida & Lahann, 2008). Since nanotechnology's rapid development a few decades ago, new unknown possibilities for smart materials applications have emerged. Professor Richard Feynman coined the term “nanotechnology” in 1959 during a conference on the future of technology held at the California Institute of Technology (Caltech). The conference's provocative title, “There is plenty of room at the bottom,” was only the beginning of what we now know as nanotechnology. Nanotechnology is an interdisciplinary field of study that combines engineering with biology, chemistry, and physics. Nanotechnology is typically seen as a scientific instrument that “steps across the limit” of downsizing, resulting in materials that behave differently compared to macroscopic scale.

More particular, as a solid substance's dimensions approach the nanoscale, its physical and chemical properties might diverge dramatically from those of the identical material at the macroscale (Gopakumar et al., 2018). Nanomaterials have evolved as a fascinating class of materials that includes a wide range of samples with at least one dimension in the 1–100 nm range. The sensible design of nanoparticles can result in extremely high surface areas. Nanomaterials can be made with magnetic, electrical, optical, mechanical, and catalytic capabilities that are vastly superior to those of their bulk counterparts. The size, shape, synthesis conditions, and appropriate functionalization of nanomaterials may all be precisely controlled to provide the desired qualities (Ahlawat & Narayan, 2020; Wellia et al., 2017). Organic (primarily polymer-based nanoparticles), inorganic (metal, metal oxide, metalloid nanoparticles), and hybrid nanomaterials are all examples of smart nanomaterials (Wieszczycka et al., 2021). Smart nano photocatalysts are light-responsive nanomaterials that trigger reactions when exposed to light. Photocatalysis is a multifunctional process that has applications in science, physics, chemical engineering, and chemistry. Photocatalysis has a wide range of benefits and applications. It is a cost-effective and simple method of producing energy, removing pollution, and reducing CO₂. The absorption of light by a solid substance initiates a photocatalytic reaction. Semiconductor photocatalysis is commonly thought to be a reaction that takes place on the semiconductor's solid surface. Because not all catalysts have photocatalytic capabilities, catalysis is classed differently.

Photocatalysis, on the other hand, considers processes that lead to energy storage and increased efficiency in pollution removal and water splitting. Non-toxic, stable, highly photoactive, and low-cost photocatalysts are suitable. Templates with zeolites were extended to micro structured silica, alumina, and other oxides by heterogeneous photocatalysis, allowing sub nanoclusters to be stabilized down to the nanoscale. The supports not only stabilize the nanoparticles, but they also act synergistically with the nanoparticle surfaces to activate substrates in a manner similar to the positive synergy reported in alloys between two transition metal atoms or between a transition metal and a main group atom (L. Liu & Corma, 2018). Nanocomposites refer to complex nanoparticle support ensembles. For a competent and well-established photocatalytic scheme, the surface properties, material selection, crystallinity, structure, electronic band, and design of a heterogeneous photocatalyst must all be carefully considered. For photocatalysis, a large surface area is advantageous because more light will absorb on it, resulting in a large number of electrons and holes for pollutant destruction. Higher crystallinity with fewer defects can reduce charge carrier recombination, which improves the material's photocatalytic efficiency during catalytic processes. Edge recombination and Fermi level trapping are reduced when the eminence boundary is large. For heterogeneous photocatalysis, material selection is critical.