Kok Yeow You

With the rising demand for efficient, sustainable and scalable energy storage, researchers are continuously exploring innovative materials for next-generation supercapacitors. Among these, transition metal coordination polymer (TMCP)-derived materials have emerged as promising candidates due to their high porosity, redox activity and structural adaptability. These materials offer significant potential for energy storage, but challenges like low electrical conductivity, structural instability and limited charge retention have restricted their widespread application. To overcome these hurdles, researchers have developed transformation strategies such as carbonization, phosphorization, sulfidation and oxide formation, enhancing the conductivity, stability and overall electrochemical performance of TMCPs. This review investigates the latest breakthroughs in TMCP-derived electrode materials, highlighting key advancements in synthesis techniques, structural engineering and hybrid material integration to improve charge transport and long-term durability. The incorporation of green chemistry principles, such as low-temperature synthesis, the use of non-toxic precursors, and strategies for recycling or reducing harmful byproducts, is highlighted, consequently promoting the fabrication of environmentally friendly supercapacitors. Furthermore, it explores how nanostructured designs and composite materials are unlocking new possibilities for high-performance supercapacitors. It also provides a perspective on the future of TMCPs in energy storage by fusing theoretical insights with experimental evidence. Theoretical frameworks like density functional theory and emerging machine learning models are other methods employed to better understand redox behaviour and drive material design. It addresses present issues and suggests viable future directions for their useful application.

Rhodamine B (RB), chrysoidine G (CHG) methylene blue (MB) are widely used in various industries for colouring, as well as other purposes. Due to their potential toxicity to humans and the environment, removing RB, CHG and MB from wastewater and process effluents is very crucial. There are varieties of techniques to remove dyes from wastewater that have been studied but adsorption is an example of a low-cost and environmental-friendly technique. In this research, magnetite reduced graphene oxide (MrGO) nanocomposites was utilized as an adsorbent to reduce or remove RB, CHG and MB concentration from aqueous solution simultaneously. The MrGO acted as an adsorbent to adsorb the dyes while the magnetic properties in the MrGO acted as separator from the treated water. FESEM, XRD, BET, FTIR and Raman are used to confirm the formation of MrGO. The highest adsorption capacities achieved by MrGO from different individual dye aqueous solutions were follow the order: CHG is 41.70 mg/g MB is 26.02 mg/g and RHB is 3.51 mg/g.

Emulsified oily wastewater which contain oil-in-water emulsions, produced by polymer flooding are extremely stable because the dissolved polymers absorbed onto oil/water interface and reducing the interfacial tension. Numerous attentions have been given to such pollution control but to remove the residual oil from emulsion for saving energy and protecting the environment continues to be a challenge in petroleum industry. A novel ternary photocatalyst, consisting of magnetite-RGO decorated with TiO₂ nanoparticles, TiO₂-Fe₃O₄-RGO nanocomposites was proposed in order to demulsify the polymer stabilized oil-in-water emulsion. Various techniques were employed to characterize TiO₂-Fe₃O₄-RGO nanocomposites. The morphology of TiO₂-Fe₃O₄-RGO nanocomposites was determined by using FESEM. From observation, TiO₂ and Fe₃O₄ particles that deposited on RGO sheets were arbitrary shape. Besides, EDX analysis shows titanium content is more than Fe. From the XRD pattern of TiO₂−Fe_3O4−RGO nanocomposites, few main peaks were found at 2θ = 25.2°, 36.2°, 37.8°, 47.6°, 54.0° and 62.5°, which were similar to the peaks of TiO₂ and Fe₃O₄ particles. The main diffraction patterns for carbon variety characteristic (002) peaks of graphene at 25.9° did not detected, it might be protected by main peaks of anatase TiO₂ at 25.2°. From RAMAN analysis, TiO₂−Fe₃O₄−RGO nanocomposites was attributed to disorder carbon (D band) signal in 1359cm⁻¹ and graphite carbon (G band) signal around 1599cm^-1. Besides, TiO₂−Fe₃O₄−RGO nanocomposites was indicated specific vibration at 315cm^-1, which can be contributed to the presence of anatase phase of TiO₂. In FTIR analysis, there are some specified stretching vibrations. The presence of Ti-O-Ti bond stretching at 797cm^-1, 781cm⁻¹ and 662cm^-1 were attributed to the good distribution of TiO₂ on reduced graphene oxide (RGO). From these analyses, TiO₂−Fe₃O₄−RGO nanocomposites was confirmed successfully synthesized. Photocatalytic demulsification of crude oil-in-water emulsion was tested using TiO₂−Fe₃O₄−RGO nanocomposite and demulsification’s efficiency was achieved more than 75%.

Oil-in-water (O/W) emulsion has been a major concern for the petroleum industry. A cost-effective magnetite-reduced graphene oxide (MRGO) nanocomposite was synthesized to study the demulsification process of emulsion using said nanocomposite under solar illumination. Characterization data show that the magnetite was successfully deposited on reduced graphene oxide through redox reaction at varying loading amounts of magnetite. Demulsification of the O/W emulsion using MRGO nanocomposite shows that in general the demulsification efficiency was dependent on the loading amount of Fe₃O₄ on the RGO sheet. It was proposed that the surfactant hydroxyl groups have an affinity towards Fe₃O₄, which the loading amount was directly proportionate to available active site in Fe₃O₄. As the loading amount increases, charge recombination centers on the RGO sheet would increase, effectively affecting the charge distribution within MRGO structure.