Graphitic carbon nitride–reduced graphene oxide (g-C3N4@r-GO) nanocomposites for photocatalytic hydrogen production by water splitting and high-performance electrochemical supercapacitors

The nanocomposites of g-C3N4 were prepared with reduced graphene oxide by reducing it with ascorbic acid (AA) and NaBH4. As-fabricated g-C3N4@r-GO nanocomposites were used in a water splitting to generate hydrogen i.e. 339.82 µmolh− 1g− 1 form the nanocomposite g-C3N4@r-GO (AA) with 2.52% apparent quantum efficiency at 420 nm, which is 5.6, 3.4, 1.6, and 1.4 times higher than their counterparts, g-C3N4, GO, g-C3N4@GO, and g-C3N4@GO(NaBH4), respectively. The composites were also tested for specific capacitance, where the composite g-C3N4@r-GO (AA) demonstrated the highest specific capacitance of 322.77 F g− 1 at 2 A/g in aqueous 2 M KOH with 78.56% charge retention after 5000 cycles at 3 A/g. The SPV study confirm the formation of effective interface with p-n junction, minimum band gap by using optical absorption, effective charge transfer using EIS, interfacial interaction, layered structure, and PLE study approve minimum charge-recombination rate in nanocomposites g-C3N4@r-GO(AA) that significantly supported the reasonable H2 generation rate as well as the good super capacitive behaviour. The substance under study guarantees a promising position in the development of the mystical material for the preparation of H2 and next-generation high-performance electrochemical supercapacitors.