Improved electrochemical properties of In2S3/g-C3N4 nanocomposite for application as anodes in lithium and sodium ion batteries

•First report on the effect of g-C3N4 on In2S3 nanoparticles used as anode for Li/Na ion battery.•g-C3N4 matrix improves the electrode/electrolyte contact through enhanced surface area and pore volume.•0.8In2S3:0.2 g-C3N4 delivers reversible capacity of ∼ 358 mAh g−1 /1000 cycles/0.5 Ag−1 in LIB.•0.8In2S3:0.2 g-C3N4 delivers reversible capacity of ∼ 302 mAh g−1 /500 cycles/0.5 Ag−1 in SIB.