Globally, the generation of waste from various industries and biomass is continuously increasing each year. Meanwhile, those waste materials are appropriate to produce nanocatalysts/value-added products used for diverse applications. Recently, the nanocatalysts derived from waste materials and their applications in environmental protection have gained more attention from researchers.

Currently, the reuse of wastewater and solid waste from domestic and various industries is very much required for a sustainable environment. Moreover, it can be a great solution when it is necessary to establish an environmentally friendly system to overcome energy, biological and environmental problems.

This Special Issue focuses on the preparation and application of different eco-friendly waste-based nanocatalyst materials in energy, environment, and biological applications such as carbon nanotubes, water purification and wastewater treatment, solid waste management, biodiesel production, fuel cell, energy applications, nanotoxicology, usage in drug delivery, photocatalytic activity and photochemical activity, etc. The aim of this Special Issue is to invite researchers and bring them together in one forum to contribute original research and review articles on the topic of eco-friendly waste-based nanocatalysts and their applications.

Potential topics include but are not limited to the following:

• Modern analytical methods for the characterization of nanocatalyst materials
• Nanocatalyst and nano-adsorbent materials in wastewater treatment
• Nanocatalyst materials for renewable and sustainable energy
• Nanocatalyst materials for solid waste management and pollution remediation
• Interaction of nanocatalyst materials with plants and microbiomes
• Bio-compatibility and safety of nanocatalyst materials
• Recent synthetic and waste-derived nanocatalyst materials
• Synthesis approaches of waste-derived nanoparticles and nanocatalysts in environmental applications and sustainability considerations
• Nanoparticles and nanocatalyst materials in pesticides and bioremediations
• Nanoparticles and nanocatalyst materials in agricultural production and crop protection
• 2D and 3D nanocatalyst material