Photocatalysis using polluted water where organic pollutants act as electron and hole transferring agents and carbon dots (C-Dots) act as a photosensitizer is a new game-changing approach for next generation photocatalysis. We demonstrate here an excellent approach for photocatalysis using water-soluble pollutants as a sacrificial electron acceptor (benzoquinone, BQ) and a sacrificial hole acceptor (pyrazine, PYZ), creating a mimic of untreated wastewater. BQ and PYZ are two common pollutants which are found in industrial wastewater. Here, charge separation and recombination processes are investigated to find out the exact mechanism for an efficient homogeneous photocatalysis process with myriad uses of steady state, time-resolved photoluminescence and ultrafast transient absorption spectroscopy. Furthermore, we demonstrate the proof of concept in charge separation using wastewater pollutants which may provide a new cost-efficient approach for improving the efficiency of photocatalysis, where we found that the efficiency of methylene blue and rhodamine B degradation is improved in the presence of pollutants with a photosensitizer (C-Dots). This finding will create a new avenue for the design and development of cost-efficient solar-driven hydrogen production and improvement of photocatalytic activity using untreated wastewater.

Photostable perovskite quantum dot (PQD)-based composite systems have huge potential for optoelectronic and photocatalysis applications. Herein, we have synthesized hydrophobic carbon dots (NC-Dots) and made a composite system with PQD to improve the stability of the material and establish a new generation of advanced materials for future applications. However, there is a lack of fundamental understanding of the dynamics and charge separation mechanism in PQD and NC-Dot-based composite systems, which is essential to interpret the degree of efficiency. In this context, we have also synthesized composites of PQD and different co-doped (boron and phosphorus) NC-Dots to explore the complete scenario of carrier dynamics. This would help in finding the appropriate composite system for photocatalysis. The ultrafast studies show that the carrier-transfer process depends on the dopant of the NC-Dots. The PQD-NC-Dots and PQD-phosphorus doped-NC-Dots (PQD-P-NC-Dots) tend to demonstrate unidirectional carrier transfer, while the PQD-boron-doped C-Dots (PQD-B-NC-Dots) are found to be bidirectional carrier-transfer in the hot states. This is the first investigation on the effect of doped NC-Dots on the multiexciton dissociation in the PQD composite systems that showed a direct relationship with the photocatalytic efficiency. This proof of concept in multielectron dissociation and directional carrier transfer may provide a new approach to improve the efficiency in optoelectronics, photocatalysis, and other similar applications.

Designing of Carbon Dots (C-Dots) in a controlled way requires a profound understanding of their photo-physical properties such as the origin of fluorescence, excitation wavelength-dependent emission properties, which is a...

The unique chiral properties exhibited by nanoscale materials and their preferable interactions with the helicity of free-standing protein-based biopolymers offer a novel platform for developing spintronic applications. We investigated the chiroptical effect in charge transfer processes in a chiral carbon dot (C-Dot)-doped biopolymer, specifically a free-standing proteinbased film composed of bovine serum albumin (BSA). Here, we reveal a chiroptical effect in the charge transfer process, indicating spin selectivity of the charge carriers by measuring the circular dichroism spectra and by conducting an electrical study of the chiral C-dot-doped BSA film. To our knowledge, this is the first study to investigate chiral-selected electron transfer through a freestanding chiral C-Dot-doped protein-based film. Our results provide new insights into the chiral properties of materials and suggest potential applications in the development of chiral-sensitized bioelectronic devices, including the fabrication of chiral electrodes. These advancements in biopolymer-based chiral electronics could have important implications in biosensing, drug delivery, and other biomedical applications.

Inorganic perovskite quantum dots (PQDs) have great potential for optoelectronic applications as a result of their tunable optical properties, significant absorption coefficient, and high mobility. Combining PQDs with molecular adsorbates offers exciting possibilities for future applications, making it important to study interfacial electron transfer in PQD–molecular composites. Here, we present a study of PQD and hemin composites (PQD–hemin) to understand how their interfacial electron transfer dynamics are affected by adsorbate and PQD properties. Our femtosecond ultrafast transient absorption and time-resolved photoluminescence (TRPL) studies reveal that hot carrier relaxation, charge separation, and charge recombination processes are significantly impacted in the PQD–hemin composite system under different excitations, both higher and lower energy. Additionally, our alternating current (AC)- and direct current (DC)-bias-driven electrical studies show that, despite efficient charge separation in the PQD–hemin composite system, the light-induced transient photocurrent drops. The findings on the PQD–molecular composite will give useful outlooks for designing a variety of optoelectronic devices.