Open Access
Article
21 November 2025Effect of Support Preparation Method on the Performance of Ni/SrTiO3 Catalysts for Dry Reforming of Methane
Dry reforming of methane (DRM) offers an efficient route to simultaneously convert CH4 and CO2 into synthesis gas (H2/CO), a key intermediate to produce fuels and valuable chemicals. Ni-based catalysts are regarded as the most promising candidates due to their high activity and low cost; however, their stability remains a major obstacle under the DRM conditions. Perovskite-type oxides such as SrTiO3 possess high thermal stability, tunable composition, and strong metal-support interactions, making them ideal to enhance the dispersion and durability of Ni species. In this study, Ni/SrTiO3 catalysts were synthesized via co-precipitation (CP), hydrothermal (HT), and sol-gel (SG) methods, and were comprehensively characterized before and after the reaction. The characterizations revealed that all samples preserved the perovskite framework after reduction and reaction. Among them, Ni/HT-STO and Ni/SG-STO exhibited larger surface areas (18.8 and 13.9 m2·g−1) and higher initial CH4 conversions (66.3% and 68.9%) than Ni/CP-STO (44.8%). However, Ni/HT-STO underwent rapid deactivation, with CH4 conversion decreasing to 21.2% after 60 h due to severe carbon accumulation (12.4 wt%) and notable Ni particle growth. In contrast, the sol-gel derived Ni/SG-STO maintained a higher activity (25.6% after 60 h) with moderate carbon deposition (9.2 wt%) and showed the smallest Ni particle growth of only 2.64 nm (from 14.91 to 17.55 nm), compared with 4.29 nm for Ni/CP-STO (25.83 to 30.12 nm) and 6.08 nm for Ni/HT-STO (27.12 to 33.20 nm). Temperature-programmed surface reaction (TPSR) analysis further revealed that Ni/SG-STO exhibited a more balanced CH4 activation and CO2 dissociation, enabling efficient carbon-oxygen coupling and inhibiting graphitic carbon formation. Overall, these results demonstrate that the sol-gel method effectively enhances the anti-sintering and anti-coking performance of Ni/SrTiO3 catalysts.
Open Access
Article
01 December 2025Preparation, Characterization and Performance Assessment of Metal Complexes of Curcuma longa Extract as Sensitizers for Dye-Sensitized Solar Cells
The dye extract of Curcuma longa (turmeric), which is very rich in curcumin, was chemically modified by complexation reaction with Zn2+, Cu2+, and Fe3+ ions to enhance its stability, electron transfer and photovoltaic performance. The dye and complexes were characterized by Ultraviolet-Visible (UV-Vis) absorption and Fourier Transform Infra-Red (FTIR) spectroscopy of potential chromophores and functional groups. The spectral data obtained indicated that the curcuminoid ligands were successfully coordinated with the metal centers, resulting in red-shifted absorption bands from beyond 460 nm and C=O vibrational frequency decreasing below 1650 cm−1. Complexation reaction resulted in improved photochemical response and enhanced light-harvesting potential. When compared, the solar cells fabricated with titanium dioxide (TiO2) photoanodes sensitized by the complexes afforded improvement in the magnitude of short-circuit current density as well as power conversion efficiency compared to the devices sensitized with the crude extract. Among the three complexes, the Zn-complex afforded the highest efficiency (1.20%), attributed to favourable electronic coupling and reduced recombination losses. Computational studies conducted through quantum chemical calculations based on the curcumin structure supported the experimental findings. The findings from this study demonstrate that metal ions-natural dye complexes have potential for application as low-cost, eco-friendly and sustainable sensitizers, thereby opening a novel horizon in green photovoltaic technologies.
Open Access
Article
09 December 2025Demethylation of Lignin from Rice-Straw Biorefinery: An Integrated Chemical and Biochemical Approach
The efficiency of lignocellulosic biorefineries is limited because of the high recalcitrance and low reactivity of lignin. The reactivity of lignin can be enhanced through various chemical and biochemical approaches. Demethylation is one of the methods that improve the availability of phenolic hydroxyl groups in lignin, thereby enhancing its reactivity and application in sustainable adhesives. The goal of this study is to integrate microbial and chemical approaches to aid in the demethylation of lignin. Towards that end, lignin was first extracted and purified from the rice straw biorefinery solid residue obtained post ethanol fermentation. This rice straw lignin was then subjected to chemical and microbial demethylation. For microbial demethylation under alkaline conditions, Pseudomonas putida and Pseudomonas fluorescens were employed, while demethylation under neutral conditions was conducted using Trametes versicolor. Integrated treatment using Pseudomonas putida followed by hydrogen iodide yielded an increase in the phenolic hydroxyl content by approximately 39–43%. Demethylation using chemical methods and biological methods alone provided approximately 18–27% increases in phenolic hydroxyl content, respectively. Furthermore, to assess the physical and chemical properties of demethylated lignin, FT-IR, TGA, and morphological analytical tools were employed.
