Investigating the structural, dielectric, optical and photocatalytic properties of carbon dots and palladium, platinum decorated carbon dots

•Fluorescent carbon dots and precious metal decorated carbon dots were synthesized.•Structural, dielectric, optical and photocatalytic aspect were thoroughly investigated.•Theory and experiments unveiled the effect of Pt and Pd on the band gap energy and photocatalysis of CDs. In this study carbon dots (CDs), palladium and platinum decorated carbon dots (Pd-CDs, Pt-CDs) were synthesized by hydrothermal method. The synthesized materials were characterized by Transmission Electron Microscope (TEM), X-ray Diffractometer (XRD), Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Photoluminescence (PL) and impedance analyzer. Photoluminescence study revealed that the CDs, Pd-CDs and Pt-CDs were fluorescent in nature. A comparative study was conducted to investigate the energy storage capacity of the different materials. The photocatalytic properties of the materials were studied through the degradation of Acid Red 4(AR-4) a member of azo dyes. For better photocatalysis optimized reaction parameters were concentration; 10 ppm, temperature; 328 K, time; 120 min and catalyst amount; 0.12 g/20 ml. Photocatalysis for Pt-CDs was observed superior than Pd-CDs and CDs. The degradation of AR-4 over Pt-CDs follows first order kinetics with rate constant of 2.2 × 10−3 min−1. Both experimental and theoretical findings revealed that the Pt decorated CDs have high catalytic activity due to its low band gap energy 1.235 eV as compared to CDs and Pd decorated CDs. Catalysts used for photodegradation exhibited exquisite regeneration capacity with minimal loss in activity.