Polyoxometalate (POM) supported metal complex has proved to be a suitable catalyst for waterreduction/oxidation in recent studies. To catalyze hydrogen evolution reaction (HER), we have employed aPOM-based inorganic-organic hybrid compound [Cu^II(2,2′-bpy)(H₂O)₂Cl][Cu_II(2,2′-bpy)(H₂O)₂Al(OH)₆-Mo₆O₁₈].4H2O (1) with a spiral-chain-like structure consisting of Anderson type polyoxometalate,[Al(OH)₆Mo₆O₁₈]^3- onto which Cu-complex, [Cu(H₂O)₂(bpy)]²⁺ fragments are supported. This compoundacts as a pre-catalyst towards forming the active catalyst for catalyzing hydrogen evolution reaction (HER) bywater reduction in a neutral medium. The active catalyst derived from this compound 1 achieves a currentdensity of 1 mA/cm² at an overpotential of 348 mV. The turnover frequency calculated for the active catalystis found to be 1.780 [mol H₂ (mol Cu)^-1s^-1] with the Faradaic efficiency of 85%.

A unique electrochemical structural rearrangement under the electrochemical condition observed for a chain-like structured Cu-complex supported on Anderson type polyoxometalate,[Cu^II(2,2′-bpy)(H₂O)₂Cl][Cu_II(2,2′-bpy)(H₂O)₂Al(OH)₆-Mo₆O₁₈].4H2O (1) resulting in the formation of the active catalyst for the electrochemical HER activity. The active catalyst achieves the current density of 1 mA/cm² with an overpotential of 348 mV with faradic efficiency of 85% at neutral pH.

Metal-free photocatalysis is a sustainable and environmentally friendly method of transforming solar energy into molecules with added value. A light-harvesting photocatalyst without metal Phloxin-B (P-B)in-situ edge functionalized graphitic carbon nitride (g-C₃N₄) was assembled to enable the solar-light responsive photocatalytic C-H bond arylation and NADH regeneration cofactor. The photocatalytic performance was examined to estimate the C-H bond arylation and NADH regeneration efficiency by g-C₃N₄/P-Bcomposite photocatalyst. The charge carrier transfer of g-C₃N₄ was found to be stimulated by the lightharvester P-B layer, increasing the efficiency of chemical synthesis under solar light irradiation. In light ofthis, the g-C₃N₄/P-B composite photocatalyst exhibits high photocatalytic activity for the successful C-Hbond arylation (98.6%) and regeneration of NADH (70.7%). This composite photocatalyst was characterized by FTIR and UV-visible spectrum along with particle size analysis, and cyclic voltammetry (CV). This effortoffers a new and superficial technique to synthesize a highly efficient g-C₃N₄/P-B composite photocatalyst and afford a greener path for renewable energy and photocatalytic reactions.

The graphical abstract represents the highly selective g-C₃N₄/P-B photocatalyst for the C-H bond activation of 4-bromoaryldiazonium salts with furan and regeneration of NADH under solar light irradiation. The g-C₃N₄/P-B photocatalyst has been effective photocatalytic property due stacking of Phloxin-B dye (P-B) on the g-C₃N₄ sheet. NADH regenerated and C-H bond arylated products are used as substrates in the pharma industries.