Engineering of cobalt sulfide (Co5S2) microcubes for selective catalytic hydrogenation of nitroarenes and enhanced calorific value of fuel

[Display omitted] •Effect of temperature on reverse-emulsion synthesis of Co5S2 is studied.•Co5S2 particles are excellent for catalytic reduction of nitroarenes.•Synthesized product is used for enhancing the calorific values and specific gravity of diesel fuel.•High dosages of Co5S2 microparticles enhance the efficiency of fuel. Cobalt sulfide (Co5S2) cube-like microparticles are synthesized by reverse emulsion method. The elemental composition and morphology are characterized by EDX and SEM. Crystal violet, Congo red, methyl blue, methyl red, reactive black-5, 4-nitrophenol, 3-nitrophenol, 4-nitroanisole, 4-nitrobenzoic acid and 2,4-dinitrophenol are reduced by Co5S2. Effect of substituents on electron density of nitro/azo group is primary reason of different kapp values. Small size of Co5S2 particles make it feasible for increasing efficiency of diesel. Calorific value, kinematic viscosity and specific gravity are increased as additive concentration is increased from 20 to 80 ppm showing that fuel properties are affected by additive dosage.