Recent advances in food waste-derived nanoporous carbon for energy storage.

Affordable and environmentally friendly electrochemically active raw energy storage materials are in high demand to switch to mass-scale renewable energy. One particularly promising avenue is the feasibility of utilizing food waste-derived nanoporous carbon. This material holds significance due to its widespread availability, affordability, ease of processing, and, notably, its cost-free nature. Over the years, various strategies have been developed to convert different food wastes into nanoporous carbon materials with enhanced electrochemical properties. The electrochemical performance of these materials is influenced by both intrinsic factors, such as the composition of elements derived from the original food sources and recipes, and extrinsic factors, including the conditions during pyrolysis and activation. While current efforts are dedicated to optimizing process parameters to achieve superior performance in electrochemical energy storage devices, it is timely to take stock of the current state of research in this emerging field. This review provides a comprehensive overview of recent developments in the fabrication and surface characterisation of porous carbons from different food wastes. A special focus is given on the applications of these food waste derived porous carbons for energy storage applications including batteries and supercapacitors.

This review compiles very recent literature on the synthesis of porous carbon from food waste biomass and their efficient utilisation as electrode material for energy storage applications in supercapacitor devices.

Aminotriazine derived N-doped mesoporous carbon with a tunable nitrogen content and their improved oxygen reduction reaction performance.

The electrocatalytic activity of carbon materials is highly dependent on the controlled modulation of their composition and porosity. Herein, mesoporous N-doped carbon with different amounts of nitrogen was synthesized through a unique strategy of using a high nitrogen containing CN precursor, 3-amino 1,2,4 triazine (3-ATZ) which is generally used for the preparation of carbon nitrides, integrated with the combination of a templating method and high temperature treatment. The nitrogen content and the graphitisation of the prepared materials were finely tuned with the simple adjustment of the carbonisation temperature (800-1100 °C). The optimised sample as an electrocatalyst for oxygen reduction reaction (ORR) exhibited an onset potential of 0.87 V vs. RHE with a current density of 5.1 mA cm-2 and a high kinetic current density (Jk) of 33.1 mA cm-2 at 0.55 V vs. RHE. The characterisation results of the prepared materials indicated that pyridinic and graphitic nitrogen in the carbon framework promoted ORR activity with improved four-electron selectivity and excellent methanol tolerance and stability. DFT calculations demonstrated that the structural and planar defects in the N-doped carbon regulated the surface electronic properties of the electrocatalyst, leading to a reduction in the energy barrier for the ORR activity. This strategy has the potential to unlock a platform for designing a series of catalysts for electrochemical applications.

Fabrication of Mesoporous C60/Carbon Hybrids with 3D Porous Structure for Energy Storage Applications.

We report on the synthesis of 3D mesoporous fullerene/carbon hybrid materials with ordered porous structure and high surface area by mixing the solution of fullerene and sucrose molecules in the nanochannels of 3D mesoporous silica, KIT-6 via nanotemplating approach. The addition of sucrose molecules in the synthesis offers a thin layer of carbon between the fullerene molecules which enhances not only the specific surface area and the specific pore volume but also the conductivity of the hybrid materials. The prepared hybrids exhibit 3D mesoporous structure and show a much higher specific surface area than that of the pure mesoporous fullerene. The hybrids materials are used as the electrodes for supercapacitor and Li-ion battery applications. The optimised hybrid sample shows an excellent rate capability and a high specific capacitance of 254 F/g at the current density of 0.5 A/g, which is much higher than that of the pure mesoporous fullerene, mesoporous carbon, activated carbon and multiwalled carbon nanotubes. When used as the electrode for Li-ion battery, the sample delivers the largest specific capacity of 1067 mAh/g upon 50 cycles at the current density of 0.1 A/g with stability. These results reveal that the addition of carbon in the mesoporous fullerene with 3D structure makes a significant impact on the electrochemical properties of the hybrid samples, demonstrating their potential for applications in Li-ion battery and supercapacitor devices.