rGO–diaminobutane surfaces with optimized N doping and hydrodynamics as dual proton–electron conductors and carbon photocatalysts

Abstract

The hybrids of reduced graphene oxide (rGO) and diaminoalkane (DAA) including rGO–DAP, rGO–DAB, and rGO–DAPN (DAP = 1,4-diaminopropane, DAB = 1,4-diaminobutane and DAPN = 1,4-diaminopantane) were synthesized by solventless vapor phase reduction of the respective GO-hybrids, namely, GO–DAP, GO–DAB, and GO–DAPN. Within this rGO–DAA series, the optimization of N-doping, electronic conductivity (EC), and water dynamics (evaluated by the measurement of the proton conductivity value) is observed in rGO–DAB. The EC of rGO–DAB is 1.72 μA V⁻¹, which is higher than the EC of reported rGO–alkylamine (rGO–AA) hybrids. The PC of rGO–DAB is ≈10⁻³–10⁻⁴ S cm⁻¹, which is slightly less than that of pristine GO. The extent of N doping at the graphitic carbon skeleton is 6.7%, which is higher than that of all the reported rGO–AA hybrids. The rGO–DAB could afford photocatalytic water splitting (WS) and dye degradation (DD). The efficiency toward WS is 18.48 μmol h⁻¹ g⁻¹, whereas the efficiency toward the degradation of methylene blue (MB) revealed a k_LH value of 0.015 min⁻¹. Both these values are higher than those of the reported rGO–AA hybrids. The DAP precursor contributes to N doping in rGO. The hybrids thus function as bandgap semiconductors and aid light-harvesting photocatalysis. The high EC and super-fast hydrodynamics supported the electron mediation and propagation of water/MB molecules to the N-doped center during reactions. Therefore, in addition to the generation of electron/hole pairs, the materials can trigger the mechanistic pathway of photocatalysis. These findings suggest that the catalytic activity of rGO-based materials can be improved not only by engineering the surface and bandgap property but also by improving the electronic conductivity and hydrodynamics within the staked layers of rGO.