This work aims to enhance the value of palm empty fruit bunches (EFBs), an abundant residue from the palm oil industry, as a precursor for the synthesis of luminescent carbon dots (CDs). The mechanism of fIuorimetric sensing using carbon dots for either enhancing or quenching photoluminescence properties when binding with analytes is useful for the detection of ultra-low amounts of analytes. This study revealed that EFB-derived CDs via hydrothermal synthesis exceptionally exhibited luminescence properties. In addition, surface modification for specific binding to a target molecule substantially augmented their PL characteristics. Among the different nitrogen and sulfur (N and S) doping agents used, including urea (U), sulfate (S), p-phenylenediamine (P), and sodium thiosulfate (TS), the results showed that PTS-CDs from the co-doping of p-phenylenediamine and sodium thiosulfate exhibited the highest PL properties. From this study on the fluorimetric sensing of several metal ions, PTS-CDs could effectively detect Fe³⁺ with the highest selectivity by fluorescence quenching to 79.1% at a limit of detection (LOD) of 0.1 µmol L⁻¹. The PL quenching of PTS-CDs was linearly correlated with the wide range of Fe³⁺ concentration, ranging from 5 to 400 µmol L⁻¹ (R² = 0.9933).

This work explores silica (SiO₂) extraction from sugarcane bagasse ash using NaOH solution. The obtained SiO₂ with 98 wt% purity is further used to synthesize zeolite NaA for CO₂ adsorption, showing comparable capacity to commercial NaA.

Carbon dioxide (CO₂) conversion into fuels and valuable chemicals driven by sunlight is a promising method for solving global warming and the shortage of fossil-derived chemicals simultaneously. Two-dimensional graphiticcarbon nitride (g-C₃N₄) has been viewed as a highly favorable material for photocatalytic CO₂ reduction. However, its overall performance is relatively low due to poor charge separation. Engineering the g-C₃N₄ structure by introduction of a carbon (C) vacancy is an effective strategy to mitigate severe charge recombination, while amine groups (–NH₂) could be beneficial for CO₂ capture. Herein, we present a facile method for spontaneous growth of amine-functionalized g-C₃N₄ with rich C vacancies by adding trace Ni²⁺ ions during thermal treatment. Insightful investigation by various advanced characterizations revealed that the carbon defects could induce a microporous structure, resulting in high surface area. In addition, the resultant defects upshift the conduction band of g-C₃N₄ and promote charge carrier separation. Both of these contribute to enhanced CO₂ reduction ability. Meanwhile, the exposed edge amino enhances the CO₂ adsorption strength, as verified by both experimental and theoretical results. When coupled with the [Co(bpy)₃]²⁺ molecular cocatalyst, the amine-rich g-C₃N₄ nanotubes with Ni²⁺ ion-induced carbon defects (Cv-CN) exhibit a superior visible-light-induced CO₂-to-CO conversion rate of 330 μmol g^–1 h^–1, which is 66-fold and 3-fold higher than those of bulk g-C₃N₄ (bulk CN, 5 μmol g^–1 h^–1) and g-C₃N₄ nanotubes (CN, 120 μmol g^–1 h^–1), respectively, in a liquid–gas phase reaction. Density functional theory (DFT) calculations demonstrate that carbon vacancy introduction creates edge amino groups capable of forming strong hydrogen bonds with CO₂ molecules, resulting in a 13-fold enhancement in adsorption energy from −0.01 to −0.13 eV. This work offers a facile and spontaneous strategy for synthesizing high-reactive g-C₃N₄ for photocatalytic CO₂ reduction.