Glucose derived carbon quantum dots on tungstate-titanate nanocomposite for hydrogen energy evolution and solar light catalysis

Glucose derived carbon quantum dots (CQDs) modified tungstate–titanate were synthesized with various CQDs ratios to act as highly efficient photo and electro-catalyst. X-ray diffraction (XRD) and Scanning electron microscopy (SEM) study confirmed composite formation and aggregated structures with inner voids, respectively. Diffuse reflectance spectra (DRS) revealed that absorption of light is stretched to visible region. The reduced recombination rate was obvious with reduced photoluminescence intensity. For Hydrogen evolution reaction (HER), CQDs/tungstate–titanate composites, proved catalytically more active due to active tungstun sites in consort with titania. CQDs offer additional active sites for dropping recombination rate and adsorption sites for hydrogen ions in HER. The electro composites with 1.5 mL CQDs exhibited the highest current density (ca. 190 mA/cm2) and lowest overpotential (ca. 200 mV) attributed to excellent electron transfer abilities. The cost effective and efficient electrocatalyst provides low overpotential corresponding to high current density and small Tafel slope. The catalyst proved bi-functional and had shown excellent efficiency towards solar induced photodegradation of Rhodamine Blue. Such catalyst might be persuading more progress in novel hybrid structures for energy-oriented and photocatalytic applications with facile and cost effective synthetic routes, exhibiting outstanding photo- and electrocatalytic efficiencies with remarkable stability.