Pharmaceuticals are increasingly significant contaminants in the environmental ecosystem, prompting the exploration of photocatalysis as a promising method for removing their pollutants. However, the application of semiconductor metal oxides as photocatalysts has been limited by issues such as rapid photocarrier recombination and high band gap energy. One emerging strategy to enhance the photocatalytic performance of metal oxides involves integrating them with carbon dots, which offer advantages including low toxicity, aqueous stability, increased surface area, cost effectiveness, biocompatibility, and chemical inertness. In this study, we conducted a critical review focusing on the nanocomposite development of metal oxide/carbon dots for the photocatalytic removal of pharmaceutical pollutants. Our study highlights that carbon dots can significantly enhance the photocatalytic efficiency of these metal oxides as photocatalytic materials by improving the adsorption of organic pollutants and enhancing light absorption in the visible spectrum. This review aims to provide insights for future research aimed at advancing the development of enhanced photocatalytic metal oxide/carbon dot nanocomposites.

Biomass, though a major energy source, remains underutilized. Biochar from biomass pyrolysis, with its high porosity and surface area, is especially useful as catalyst support, enhancing catalytic activity and reducing electron recombination in photocatalysis. Indonesia, the world’s top palm oil producer, generated around 12 million tons of empty fruit bunches (EFBs) in 2023, making EFBs a promising biochar source. This study synthesizes biochar from leftover EFB fibers at 500, 800, and 1000 °C, analyzing structural changes via infrared and Raman spectroscopy, along with particle size and surface area analysis, laying the groundwork for future biochar research. The smallest particle size and highest surface area gained was 71.1 nm and 10.6 × 10² m²/g. Spectroscopic analysis indicates that biochar produced at 1000 °C has produced nano-crystalline graphite with a crystallite size of approximately 5.47 nm. This provides higher defect density, although with lower conductivity. Other studies indicate that our biochar can be used as catalyst support for various green energy-related applications, i.e., counter electrodes, electrocatalysts, and photocatalysts.

KCC-1, a nanostructured silica with a bicontinuous concentric lamellar (bcl) morphology, can act as micro-reflectors to improve light-harvesting in dye-sensitized solar cells (DSSCs) using its open channel structure and low refractive index.