Inorganic nanocrystal-carbon composite derived from cross-linked gallic acid derivative of polyphosphazenes for the efficient oxygen evolution reaction

The development of heteroatoms doped inorganic nanocrystal-carbon composites (INCCs) has attained a great focus for energy applications (energy production and energy storage). A precise approach to fabricate the INCCs with homogenous distribution of the heteroatoms with an appropriate distribution of metal atoms remains a challenge for material scientists. Herein, we proposed a facile two-step route to synthesize INCC with doping of metal (α-Fe 2 O 3 ) and non-metals (N, P, O) using hydrogel formed by treating hexachlorocyclotriphosphazene (HCCP) and 3, 4, 5-trihydroxy benzoic acid (Gallic acid). Metal oxide was doped using an extrinsic doping approach by varying its content and non-metallic doping by an intrinsic doping approach. We have fabricated four different samples (INCC-0.5%, INCC-1.0%, INCC-1.5%, and INCC-2.0%), which exhibit the uniform distribution of the N, P, O, and α-Fe 2 O 3 in the carbon architecture. These composite materials were applied as anode material in water oxidation catalysis (WOC); INCC-1.5% electro-catalyst confirmed by cyclic voltammetry (CV) with a noticeable catholic peak 0.85 V vs RHE and maximal current density 1.5 mA.cm −2 . It also delivers better methanol tolerance and elongated stability than RuO 2 ; this superior performance was attributed due to the homogenous distribution of the α-Fe 2 O 3 causing in promotion of adsorption of O 2 initially and a greater surface area of 1352.8 m 2 /g with hierarchical pore size distribution resulting higher rate of ion transportation and mass-flux. Graphical abstract