Thermophysical properties and contact angle of ethylene glycol/2D graphitic carbon nitride nanofluids with different metal substrates for solar applications

•The 2D graphitic carbon nitride is prepared by combustion approach.•Thermal conductivity increases with the increase of wt.% of 2D g-C3N4 nanofluid.•Viscosity decreases with the increase of wt.% of 2D g-C3N4 in base fluid.•Wettability of Al is 7.7° for 90:10% EG/W @ 0.05 wt% of 2D g-C3N4. In this work, two dimensional graphitic carbon nitride (2D g-C3N4) nanomaterials is prepared by the combustion approach. The synthesised material is analysed for its structural and morphological properties using X-ray diffractometer and Transmission electron microscopy instruments. Further, pure ethylene glycol (EG), 90:10%, 70:30%, and 50:50% combination of EG/Water are used as base fluid to prepare 0.01, 0.03 and 0.05 wt% concentrations of 2D g-C3N4 nanofluids. The main objectives of this study are to find thermal conductivity, viscosity and contact angle of 2D g-C3N4 based nanofluids. The thermal conductivity of nanofluids increases with the increase of wt.% of 2D g-C3N4 in EG/Water. The viscosity of nanofluids decreases with the increase of concentrations of 2D g-C3N4 in EG/Water. It is found that the 50:50% combination of EG/water with 0.05 wt% of 2D g-C3N4 nanofluids exhibit enhanced thermal conductivity and low viscosity than other combinations. Further, Different concentrations of nanofluids are dropped on copper, aluminium, mild steel and stainless steel substrates to study the static contact angle. Results reveal that aluminium substrate exhibit excellent wettability (θ = 7.7°) with the combination of 90:10% (EG/Water) with 0.05 wt% of 2D g-C3N4. This study can deliver the effective performance in solar collectors, solar steam generation, solar heating and cooling.