Muhammad Sohail

Rice straw is an agricultural byproduct primarily produced in Asian regions. It is crucial to discover an effective method for converting this waste into chemicals that can be utilized to substitute goods derived from fossil fuels. Pyrolysis serves as an interesting procedure to obtain bio-oil from this rice straw. The composition of the bio-oil obtained after the pyrolysis procedure contains a small quantity of value-added chemicals in addition to various gas components in the gas product. Therefore, the development of catalytic systems that improve this pyrolytic reaction is mandatory. Herein, the design of a dual catalyst bed (CEM/ZSM-5) that catalyzes the volatiles that it releases has been developed. The highest output of 42.1 wt.% of bio-oil, 29.9 wt.% of gases and 28.0 wt.% of bio-char was obtained. Nevertheless, the inclusion of single zeolites to biomass yields biofuel outputs of 42.8 wt.%, gas yields of 27.7 wt.%, and a bio-char yielding of 29.5 wt.%. Additionally, the addition of cement to biomass results in a bio-oil yield of 40.4 wt.% and 30.5 wt.% of gas, along with 29.1 wt.% of char. Regarding pyrolysis gas products, the H2 yield in the produced biogas was increased from 35.9 mL/g to 45.7 mL/g, and the CH4 output was increased from 21.1 mL/g to 27.4 mL/g. The bioenergy output was evaluated employing GC-FID and GC-MS (gas and biofuel). The dual catalytic bed had a significant impact on the contents of the generated biofuel, increasing the quantity of hydrocarbons and other value-added compounds.

Light-driven heterogeneous photocatalysis has gained great significance for generating solar fuel; the challenging charge separation process and sluggish surface catalytic reactions significantly restrict the progress of solar energy conversion using a semiconductor photocatalyst. Herein, we propose a novel and feasible strategy to incorporate dihydroxy benzene (DHB) as a conjugated monomer within the framework of urea containing CN (CNU-DHBx) to tune the electronic conductivity and charge separation due to the aromaticity of the benzene ring, which acts as an electron-donating species. Systematic characterizations such as SPV, PL, XPS, DRS, and TRPL demonstrated that the incorporation of the DHB monomer greatly enhanced the photocatalytic CO₂ reduction of CN due to the enhanced charge separation and modulation of the ionic mobility. The significantly enhanced photocatalytic activity of CNU–DHB_15.0 in comparison with parental CN was 85 µmol/h for CO and 19.92 µmol/h of the H₂ source. It can be attributed to the electron–hole pair separation and enhance the optical adsorption due to the presence of DHB. Furthermore, this remarkable modification affected the chemical composition, bandgap, and surface area, encouraging the controlled detachment of light-produced photons and making it the ideal choice for CO₂ photoreduction. Our research findings potentially offer a solution for tuning complex charge separation and catalytic reactions in photocatalysis that could practically lead to the generation of artificial photocatalysts for efficient solar energy into chemical energy conversion.

One of the most frequent ways to widen the adsorption range of carbon nitride (CN) is to add a well-known photosensitizer into its basic structure. So far, such attachments have been accomplished by using weak van der Waals forces. However, using strong covalent bonding to attach such photosensitizer with CN is yet to be determined. Here, for the first time, we covalently bonded porphyrin (5,10,15,20-tetrakis(4-(2,4-diamino-1,3,5-triazinyl) phenyl)-Porphyrin (TDP)), a renowned photosensitizer, effectively with CN by thermally balanced molecular strategy. A photoreaction system was set up for the deoxygenated conversion of CO₂ to CO under visible light, where cobalt acted as a redox controller to speed up the charge transportation, while CN-TDP worked as a CO₂ activating photocatalyst. The subsequent photocatalyst has a broader absorbance range, a greater specific surface area, and intramolecular organic connections that help to decrease the electron-hole pairs’ recombination rate. Furthermore, the average weight ratio between urea and TDP was well-tuned, resulting in a fantastic CO₂ photoconversion for CN-TDP_7.0 compared to the blank sample. This substantial increase in photocatalytic activity predicts a significant shift in CN’s specific surface area, band gap, chemical composition, and structure, as well as the efficient separation of photogenerated charge carriers from the ground state (HOMO) to the excited state (LUMO), making it a top candidate for CO₂ photoreduction. At the same time, this approach paves the path for the bottom-up fabrication of carbon nitride nanosheets.