The exponential population growth on earth has put an enormous strain on energy resources, which come in various forms like fossil fuels, geothermal energy, and so on. Currently, fossil fuels are fulfilling most of our energy requirements. However, their nonrenewable nature and the production of toxic and greenhouse gases have forced the research community to explore different renewable and nontoxic energy resources. Among different renewable energy resources, hydrogen is considered an important alternative energy source. However, the production of hydrogen (H 2 ) from water is a nonspontaneous process. Therefore, different processes like photocatalysis and photoelectrocatalysis are employed to carry out the water splitting. For these processes, there is a dire need to develop different substances that can act as catalysts. For energy applications, different metals (particularly noble metals) and metal oxides (mostly transition metal oxides) have shown promising catalytic applications in the past decade. Herein, we discuss the progress made in the synthesis of metal and metal oxide nanostructures, followed by a discussion regarding the advances made in the application of these nanostructures as photocatalysts, electrocatalysts, and photoelectrocatalysts. From an energy application standpoint, it is found that doping and heterostructure development are the most advantageous methods used to date to improve the efficiency of metal and metal oxide nanostructures. Also, the development of dye-sensitized metal oxide catalysts for energy applications is considered a powerful method to develop highly efficient photocatalysts and electro-/photoelectrocatalysts. Finally, the limitations and challenges facing the practical application of these nanostructures are also discussed.

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Tremendous progress has been made in developing highly efficient cutting-edge materials and textile surfaces by applying a wide range of nanostructures during the past few years. Due to their extraordinary and attractive features, metal and metal oxide nanoparticles (NPs) have introduced prominent novel antimicrobial, photocatalytic, stain repellence, fire retardant, and UV protective functions on textile surfaces. Unfortunately, their conventional syntheses based on physicochemical procedures often require energy-intensive processes and toxic chemicals, bringing environmental and human safety concerns. To address these issues, the latest approaches based on the biological production of NPs on polymeric material surfaces are currently being pursued. In this perspective, we present a systematic and comprehensive summary of the biological in situ and ex situ formation of metallic NPs on the surfaces of textiles and fibers. A detailed and insightful discussion on the ex situ and in situ mechanisms of nanoparticle formation from chemical compounds derived from plants and fungi is also provided. Finally, critical research gaps are identified, and prospects for efficient and sustainable nanofinishing technologies for textile surfaces using biological chemicals are provided.

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