Physical Science Research Centre

TITLE: Characterization of green-synthesized carbon quantum dots from spent coffee grounds for EDLC electrode applications

SOURCE: Chemical Physics Impact

AUTHOR: Grishika Arora (Main Author)

RESEARCH CENTRE: Physical Science Research Centre

SDG: 7

CITATION: Arora, G., Nuur Syahidah, S., Liew, C. W., Ng, C. Y., Low, F. W., Pramod, K. S., Jun, H. K.. (2024) Characterization of green-synthesized carbon quantum dots from spent coffee grounds for EDLC electrode applications. Chemical Physics Impact 9(100767): 4–10. https://doi.org/10.1016/j.chphi.2024.100767.

ABSTRACT:

This study investigates the green synthesis of carbon quantum dots (CQDs) from spent coffee grounds using a hydrothermal method, offering an eco-friendly, cost-effective, and straightforward approach to nanomaterial production. The synthesized CQDs, with particle sizes ranging from 1.6 to 4.4 nm, exhibited notable fluorescence, achieving quantum yields of 37.0 %, 54.3 %, and 63.3 % depending on the coffee source. Characterization technique, including XRD, FTIR, SEM, TEM, and BET, confirmed their structural suitability of these CQDs for energy storage applications. Their electrochemical performance was evaluated through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). Among the CQDs tested, those derived from spent Liberica coffee ground (medium roasted) demonstrated superior performance, with a discharging specific capacitance of 97.5 F/g, an energy density of 4.3 Wh/kg, and a power density of 130.6 W/kg at a current density of 0.5 A/g. Additionally, they exhibited acceptable internal resistance (Ra = 0.01 kΩ and Rab = 16.9 kΩ), indicating favourable charge transfer characteristics. These results underscore the enhanced energy storage potential of CQDs derived from spent coffee grounds. The findings not only highlight the excellent electrochemical performance but also support the viability of biomass waste as a valuable resource for advanced energy storage applications, promoting sustainable, eco-friendly technologies.

TITLE: Development of polyaniline‑tin oxide (PAni‑SnO2) as binary photocatalyst for toxic pollutant removal

SOURCE: Polymer Bulletin

AUTHOR: LOW WAI LEON (Main Author)

RESEARCH CENTRE: Physical Science Research Centre

SDG: 6, 12

CITATION:  Low, W. L., Liew, C. W., Juan, J. C., Phang, S. W. (2024) Development of polyaniline‑tin oxide (PAni‑SnO2) as binary photocatalyst for toxic pollutant removal. Polymer Bulletin 82: 313–334. https://doi.org/10.1007/s00289-024-05586-2.

ABSTRACT:

Azo dyes are commonly used as a coloring agent in the textile industry to beautify the textile products. However, due to the non-biodegradable and toxic nature of azo dyes, it is imperative to degrade the toxic dye in the textile effluent in order to prevent it from penetrating the aquatic ecosystem and causing environmental pollution. For this purpose, binary photocatalysts of polyaniline—tin oxide (PAni-SnO2) with different weight percent of SnO2 were synthesized using template-free method. The chemical structures and oxidation states of the photocatalysts were confirmed by Fourier transform infrared (FTIR) and ultra-violet visible (UV–Vis) spectroscopies, respectively. The existence of SnO2 was characterized by X-ray diffraction (XRD) analysis, while morphology of the photocatalysts was investigated by field emission scanning electron microsocopy (FESEM). Electrical conductivities of PAni-SnO2 binary photocatalysts were measured by conductivity meter showing conductivity range of 6.55 × 10–6–2.66 × 10–3 S cm−1. The photodegradation performance of PAni-SnO2 binary phorocatalysts for toxic RB5 azo dye was in the range of 30.26–72.94% in which PAni-SnO2(10%) demonstrates the highest photodegradation performance of 72.94%. This can be explained by its high surface area nanorods and nanotubes morphology that promotes electron conductivity (2.66 × 10–3 S cm−1) and for better RB5 adsorption. Also, its low band gap (1.98 eV) enabling easy excitation of electrons to form electron–hole pairs and low electron-pair recombination rate (low PL emission intensity of 7.29 × 103 a.u.) are the other factors that contribute to its excellent photodegradation performance.

TITLE: Tin-Based Anodes for Next-Generation Lithium-Ion Batteries

SOURCE: Taylor & Francis

AUTHOR: Teo Li Ping (Main Author)

RESEARCH CENTRE: Physical Science Research Centre

SDG: 7

CITATION: Teo., L. P., Buraidah, M. H., Arof, A. K. (2024). Tin-Based Anodes for Next-Generation Lithium-Ion Batteries. In Jun, H.K., & Low, F.W. (Eds.), Materials for Energy Conversion and Storage (pp. 127-158). CRC Press. https://doi.org/10.1201/9781003314424.

ABSTRACT:

Batteries, in general, are electrochemical devices that transform chemical energy into electrical energy. Lithium-ion batteries are one good example of secondary batteries that can be recharged and reused for multiple cycles. Batteries, specifically lithium-ion batteries, can be regarded as a staple in our lives and exist in every corner of the world. A single cell of lithium-ion batteries comprises a cathode, anode, electrolyte, and separator. Graphite is currently the most popular anode, and there has been much research conducted on it. In this article, we focus on tin-based materials as an alternative anode rather than graphite, as it is anticipated that such compounds have the potential to serve as an anode for future-generation lithium-ion batteries.

TITLE: Fuel Cells: Fundamental and Applications

SOURCE: Taylor & Francis

AUTHOR: Liew Chiam Wen (Main Author)

RESEARCH CENTRE: Physical Science Research Centre

SDG: 7

CITATION: Liew, C. W., Liew, S. Q., Jun, H. K. (2024). Fuel Cells: Fundamental and Applications. In Jun, H.K., & Low, F.W. (Eds.), Materials for Energy Conversion and Storage (pp. 39-60). CRC Press. https://doi.org/10.1201/9781003314424.

ABSTRACT:

Fuel cell technology is a promising solution for the future of sustainable energy. Generally, the term ‘hydrogen fuel cells’ is used interchangeably. Hydrogen fuel cells generate electricity through a chemical reaction between hydrogen and oxygen, producing water as a byproduct alongside electric power. This technology can be used for transportation, stationary power generation, and energy storage. This chapter presents an overview of fuel cell technology, its fundamental principles, and the mechanism of operating a fuel cell. The thermodynamics principle of a fuel cell related to heat energy is also discussed, as fuel cells involve energy conversion. This work also highlights the challenges in fuel cell technology development and its prospects.

TITLE: Solid-state Electrolytes for Fuel Cells Application

SOURCE: Taylor & Francis

AUTHOR: Liew Chiam Wen (Main Author)

RESEARCH CENTRE: Physical Science Research Centre

SDG: 7

CITATION: Liew, C. W., Liew, S. Q., Jun, H. K. (2024). Solid-state Electrolytes for Fuel Cells Application. In Jun, H.K., & Low, F.W. (Eds.), Materials for Energy Conversion and Storage (pp. 61-96). CRC Press. https://doi.org/10.1201/9781003314424.

ABSTRACT:

Opting for solid polymer electrolytes can be a beneficial alternative to substituting hazardous liquid electrolytes which cause solvent leakage and poor electrochemical stability. The buildup of the internal pressure in the electrochemical cell which causes the explosion and internal circuit shorting is another reason for choosing solid polymer electrolytes over liquid electrolytes. The electricity of devices using solid polymer electrolytes arises from the ionic conduction mechanism in the electrolytes. The mechanism is governed by a few parameters such as the charge of mobile ions, number of mobile ions, and mobility of ions. The factors that affect the ionic conductivity of polymer electrolytes will be discussed in detail in this chapter. These factors are vital in choosing suitable materials for the formation of polymer electrolytes. For solid polymer electrolytes, their ionic conductivity values are limited and typically fall below the level of a mS/cm. Therefore, there are many approaches to improving the ionic conductivity. This chapter discusses the development of polymer electrolytes, from past generation to current state and future aspects. In addition, this chapter presents a critical review on the parameters that govern ionic conductivity and ways of improving ionic conductivity, especially for polymer electrolytes.

TITLE: Next Generation Supercapacitors with Sustainably Processed Carbon Quantum Dots

SOURCE: Taylor & Francis

AUTHOR: Grishika Arora (Main Author)

RESEARCH CENTRE: Physical Science Research Centre

SDG: 7

CITATION: Arora, G., Sharma, T., Low, F. W., Ng, C. Y., Pramod, K. S., Liew, C. W., Jun, H. K. (2024). Next Generation Supercapacitors with Sustainably Processed Carbon Quantum Dots. In Jun, H.K., & Low, F.W. (Eds.), Materials for Energy Conversion and Storage (pp. 97-126). CRC Press. https://doi.org/10.1201/9781003314424.

ABSTRACT:

In recent years, alternative battery sources like supercapacitors and electric double-layer capacitors (EDLCs) have been receiving plenty of attention. This brief review focuses on supercapacitor fundamentals and the potential application of carbon quantum dots (CQDs) in the devices. Small nanoparticles of carbon, known as CQD, which are less than 10 nm in size and contain special qualities, have become an essential tool for known specific delivery, biological research, and many therapeutic uses. The purpose of this work is also to assemble the recent research on CQD synthesis with a specific focus on the biomass of coffee grounds, their characterization methods, and the recent progress of CQDs in energy devices. For the synthesis of CQDs, two different types of synthesis methods—a top-down approach and a bottom-up approach—are employed. The laser ablation method, electrochemical method, and arc-discharge method are examples of top-down techniques. The acidic oxidation, microwave-assisted method, and hydrothermal method are examples of bottom-up approaches. CQDs are now receiving more interest from the energy storage sector as additives in electrode material due to their distinctive electrical characteristics and critical function in hosting multiple functional groups superficially. As a result, the energy density of supercapacitors has increased with the widespread usage of CQDs in electrode materials.