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[Display omitted] • First report on C-dots derived from beetroot and Fabrication of 0D/0D C-dots@CdS heterostructured photocatalysts. • C-dots@CdS showed superior activity with H 2 evolution rates of 1582 µmolg−1 than the pristine CdS (849 µmolg−1). • Achieved 97.3 % degradation efficiency of CV dye under visible light for C-dots@CdS. • The presence of C-dots in heterojunction increases the charge carrier separation leading to highest photocatalytic activity. Carbon dots (C-dots) developed from beetroot is used for the rational design of cadmium sulphide based heterojunction photocatalysts (C-dots@CdS) using hydrothermal technique. The crystal structure, phase, morphology and optical characteristics of the synthesised materials are determined using X-ray diffraction (XRD), High resolution transmission electron microscopy (HR-TEM), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV–Visible diffuse reflectance spectroscopy (UV-DRS), photoluminescence spectroscopy (PL spectroscopy), BET adsorption, X-ray photoelectron spectroscopy (XPS) and electrochemical studies. Using C-dots@CdS catalytic system, a superior photocatalytic activity relative to the undecorated CdS is observed. Among the C-dots@CdS samples, the CdS loaded with 6 wt% of C-dots exhibited enhanced hydrogen evolution rate compared with other samples considered for the study. CdS nanospheres modified with C-dots (6 wt%) resulted in the photocatalytic hydrogen evolution rate of 1582 µmolg−1 against 849 µmolg−1 evolution rate obtained for CdS nanospheres within 3 h. In spite of being 0D/0D type nano-heteroarchitecture, C-dots@CdS system obtained an apparent quantum yield of 6.37 % for the catalytic dosage of 20 mg under the irradiation of visible light. CdS in the C-dots@CdS system serves as the light harvester while C-dots with discernible edges can maintain the continuous supply of photo-excited charge carriers and hence can reduce the charge-carrier recombination. Further, the photodegradation of crystal violet dye using the optimised dosage of C-dots@CdS-6 exhibited an efficiency of 97.3 % in 120 min of visible light irradiation under neutral conditions. The detailed kinetic study reveals that the mechanism of photodegradation of crystal violet dye using C-dots@CdS system can be described using pseudo-second-order kinetics. The presence of oxygen rich hydrophilic surface functionalities of C-dots, the formation of near-surface heterojunction and the suitable band structure of C-dots@CdS system leading to the optimum charge carrier separation kinetics can be attributed to the enhanced photocatalytic performance. This work offers a promising strategy to develop bio-derived C-dots based heterojunction photocatalyst to address the burgeoning energy and environmental demands. [ABSTRACT FROM AUTHOR]

The RGO-supported HoVO 4 -ZnO nanocomposite was synthesized using the ultra sonication process. X-ray diffraction patterns, Field emission scanning electron microscopy, high resolution transmission electron microscopy, Diffractive Reflectance spectroscopy, and photoluminescence spectroscopy were employed to examine the heterostructured photocatalyst in this research study. The photocatalytic efficiency of the RGO-supported HoVO 4 -ZnO nanoparticles, under UV light irradiation, in the degradation of Rhodamine-B dye was investigated. Undoped ZnO, bare HoVO4, and HoVO 4 -ZnO, degraded at 55.6, 57.5, and 74.33 percent in 45 min, respectively. This new RGO coupled HoVO 4 -ZnO exhibits enhanced photocatalytic efficiency compared to the bare ZnO and HoVO 4 -ZnO nanocomposite. [Display omitted] • RGO coupled HoVO 4 -ZnO exhibits enhanced photocatalytic efficiency. • SEM images display existence of cavities in the lattice structure. • Incorporation of RGO into the crystal structure minimizes aggregation and crystal size. • HR TEM indicates concentric ring with occasional brilliant spots. • Narrower photoluminescence spectrum for new Nanocomposite. [ABSTRACT FROM AUTHOR]