NiO nanoflowers anchored porous gC3N4: 2D/2D heterojunction design and process optimization via response surface methodology for photocatalytic hydrogen production

• A well-designed PgC 3 N 4 /NiO NFs Z-scheme heterojunction was constructed. • The nanocomposite generated 8.47 and 5.08 times more H 2 production than pure PgC 3 N 4 and NiO NFs. • Efficient photocatalytic H 2 production was linked to the morphological and electronic features. • Response surface methodology was used to optimize the parameters. A well-designed PgC 3 N 4 /NiO NFs Z-scheme heterojunction was constructed, where 2D NiO flakes forming the 3D NFs were successfully anchored to 2D PgC 3 N 4 . The PgC 3 N 4 /NiO NFs nanocomposite generated 8.47 and 5.08 times more photocatalytic hydrogen (H 2 ) production than pure PgC 3 N 4 and NiO NFs, linked to robust separation and transfer of charge carriers, inhibited charge recombination, a high specific surface area, and improved absorption within the visible range, linked to the morphological and electronic features. An APE % of 0.74 was calculated for PgC 3 N 4 /NiO NFs, depicting efficient H 2 production. Response surface methodology (RSM) was employed for optimization of catalyst loading, methanol concentration, and time variables for optimal H 2 production, revealing 3.4 h, 164 mg catalyst loading, and 10.7 % methanol concentration as the optimal values for maximum H 2 generation. The PgC 3 N 4 /NiO NFs showed a good photostability without structural changes over four cyclic runs of photostability. Therefore, the current findings constitute a significant contribution to the fabrication of substantially effective photocatalysts for sustainable solar fuels and provide detailed insight into parameter optimization for large-scale applications.