Biomass to nanoparticles: Recent advances in the process and processing towards sustainability

The application of nanomaterials in various sectors, including biomedical, energy storage and conversion, agriculture, and the environment, is fast gaining popularity and importance. The unique properties of nanomaterials promise a faster, greener and better future, particularly its unrivalled characteristics in surface functionality, electron mobility and photoluminescence effect. However, its synthesis, processing and development have received increasing attention in recent decades, particularly in the environmental aspect. This review critically summarises and discusses recent advances in the synthesis of nanomaterials from renewable sources like biomass and the development of various processes involved. Biomass, a green, sustainable and widely available precursor, is increasingly used for synthesising nanomaterials with lower environmental burden and costs and higher biocompatibility and quality. Recent progress has seen a series of zero-dimensional (quantum dots), one-dimensional (nanotubes), two-dimensional (nanofibres) and three-dimensional (nanocrystals) nanomaterials produced from various biomass and bio-feedstock. This review also discusses the synthesis strategies involved in the processing of biomass via the top-down and bottom-up approaches, as well as the mechanisms driving such conversion. Examples for each method are discussed illustrating the preparation, synthesis and the resultant nanomaterial quality. The potential of biomass-derived nanomaterials is increasingly highlighted in various studies which promotes a transition towards greener nanomaterials.