Engineering the Catalytic Sites and Porous Framework of Biomass-Derived Carbon Aerogels for Zinc–Air Batteries and Pressure Sensors: A Review

The ever-growing global demand for sustainable energy has promoted the development of zinc–air batteries with high energy density. However, the slow multi-electron kinetic process of the oxygen reduction reaction and oxygen evolution reaction still restricts the practical commercialization of this battery technology. Biomass-based carbon aerogels can be constructed into tunable three-dimensional hierarchical structural frameworks, which provide high specific surface area and tunable structural characteristics, offering opportunities to improve mass transport and catalytic-site accessibility. This paper systematically reviews the latest research progress in the preparation and structural regulation of biomass-based carbon aerogels and elaborates on the determining effect of directional sol–gel processes, advanced drying techniques, and activation mechanisms on pore structure. To further improve the bifunctional electrocatalytic activity, this paper highlights the key doping and modification strategies, including nitrogen doping, multi-element co-doping, as well as the precise immobilization of non-noble metal nanoparticles and single-atom active sites. In addition to serving as high-efficiency, self-supporting, and flexible air cathodes for energy storage devices, the excellent mechanical rebound performance and continuous conductive network of this type of carbon aerogel also make it suitable for high-sensitivity pressure sensors. In conclusion, rational design and modification of biomass precursors can open up a green and sustainable development path for next-generation multifunctional flexible electronic devices.