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This study evaluates the critical roles of the dispersion medium and temperature during the solvothermal synthesis of nitrogen-doped reduced graphene oxide (NG) for enhancing its performance as an active material in supercapacitor electrodes. Using a fixed volume of a solvent (THF, ethanol, acetonitrile, water, N,N-Dimethylformamide, ethylene glycol, or N-Methyl-2-pyrrolidone) as the dispersive medium, a series of samples at different temperatures (60, 75, 95, 120, 150, 180, and 195 °C) are synthesized and investigated. A proper removal of the oxygen moieties from their surface and an optimum number of N-based defects are essential for a better reduction of graphene oxide and better stacking of the NG sheets. The origin of the supercapacitance of NG sheets can be correlated to the inherent properties such as the boiling point, viscosity, dipole moment, and dielectric constant of all the studied solvents, along with the synthesis temperature. Due to the achievement of a suitable synthesis environment, NG synthesized using N,N-Dimethylformamide at 150 °C displays an excellent supercapacitance value of 514 F/g at 0.5 A/g, which is the highest among all our samples and also competitive among several state-of-the-art lightweight carbon materials. Our work not only helps in understanding the origin of the supercapacitance exhibited by graphene-based materials but also tuning them through a suitable choice of synthesis conditions. 

Mesoporous cobalt- and/or iron-substituted aluminophosphates were synthesized by a hydrothermal method, followed by pyrolysis and calcination. The substitution of the transition metal elements modified the electronic properties of the samples and the accompanying surface characteristics. The samples showed tunable catalytic activity through the substitution of Fe and/or Co. We have demonstrated that the light-induced photocatalytic 4-nitrophenol reduction reaction can be enhanced through the substitution of Fe and/or Co in aluminophosphates. The induction time associated with the three different types of samples, observed due to the influence of the substituents, allows us to understand the mechanism of the 4-nitrophenol reduction process in our samples. Our work solves the issue associated with the origin of induction time and the enhancement of the catalytic activity of mesoporous aluminophosphates in the 4-nitrophenol reduction reaction through a controlled modification of the electronic properties.