Beyond chemical catalysis: laser production of clean energy

Abstract

Laser ablation in liquids (LAL) has attracted widespread attention over the last decade and has gradually become an irreplaceable technique for synthesizing nanocrystals and fabricating functional nanostructures because LAL can offer effective solutions to some challenging issues in the field of nanotechnology. In the last few years, we have witnessed exciting developments in the understanding of LAL and its application for fabricating unique nanostructures, especially in the application of LAL-generated nanomaterials to biomedicine, the environment, and energy production. Following the development of LAL, we very recently developed a simple, clean, and efficient LAL-based technique, laser bubbling in liquids (LBL), to produce clean energy through hydrogen production, carbon dioxide reduction, ammonia synthesis, etc. A series of chemical reactions occur inside micro- and nanobubbles under the extreme thermodynamic state induced by a laser at normal temperature and pressure upon LBL. Compared with traditional catalytic chemical reactions, the chemical reactions that occur in the LBL process have the following characteristics. Thermodynamically, the far-from thermodynamic equilibrium state with a high temperature inside micro- and nanobubbles created by LBL provides microenvironments for chemical reactions that typically require catalyst assistance in the absence of a catalyst. In terms of kinetics, the rapid quenching of micro- and nanobubbles confined by the liquid enables accurate control of the chemical reaction and reduces the generation of byproducts. Laser production of clean energy via LBL can be expected to be a simple, green, and efficient technique on an industrial scale under normal conditions beyond chemical catalysis. This review surveys the discovery and application of LBL and provides a comprehensive understanding of laser production of clean energy and a perspective for the further development of LBL.