Muhammad Ahmad

Bio: Muhammad Ahmad is an academic researcher from City University of Hong Kong. The author has contributed to research in topics: Electrode & Adsorption. The author has an hindex of 2, co-authored 8 publications receiving 17 citations.

An oriented Ni–Co-MOF anchored on solution-free 1D CuO: a p–n heterojunction for supercapacitive energy storage

Abstract: Herein, we propose an effective strategy to enhance the electrochemical activity of a metal organic framework-based (MOF) electrode material for electrochemical capacitors. The fabrication involves the synthesis of CuO nanowires on a Cu substrate through a facile solution-free dry oxidation route followed by the deposition of an oriented Ni–Co-zeolitic imidazolate framework (Ni–Co-ZIF) on 1D CuO. This synthesis strategy benefitted from the highly exposed redox active sites of the aligned Ni–Co-ZIF, an “ion and electrolyte repository”, to assist the diffusion of electrolyte ions, and a p–n heterojunction between CuO and the Ni–Co-ZIF. ZIFs represent an emerging and unique class of MOFs. The oriented pseudocapacitive Ni–Co-ZIF@CuO composite electrode yielded excellent electrochemical merits including a high gravimetric capacitance which is 3.3- and 2.1-fold higher than those of the self-supported CuO and bulk MOF, respectively. Furthermore, we employed first principles density functional theory calculations to study the enhanced electronic conductivity and reduced work function of Ni–Co-ZIF@CuO systems upon CuO doping, which reinforced the experimental findings. Moreover, an asymmetric supercapacitor (ASC) device was assembled to evaluate the application of the as-fabricated electrode material for electrochemical capacitors. The gadget delivered a maximum energy density of 43 W h kg−1, with improved cycling stability after 10 000 cycles. The oriented Ni–Co-ZIF@CuO with remarkable electrochemical activity and mechanical flexibility inspires for next-generation MOF-based electrode materials with superior electrochemical attributes.

High entropy alloys as electrode material for supercapacitors: A review

Abstract: Energy storage devices play an important role in our daily lives. As a kind of new materials, high-entropy alloys (HEAs) avoid the traditional “base element” concept and display a variety of interesting and unusual properties. HEAs have been considered promising electrode materials for energy storage and conversion technologies due to their excellent mechanical, chemical, and physical properties. Herein, we report a review on basic supercapacitor, such as differences in charge storing mechanism of electric double layer capacitive (EDLC)-, pseudocapacitive-, and battery-type electrode materials; differences in symmetric, hybrid, and asymmetric supercapacitor devices; and recent advances in HEAs as an electrode material for supercapacitors. The aim of this review is to combine newly emerge HEAs electrode materials with the basic concepts of supercapacitor and avoid the inflating misinterpretation in between the different energy storage systems. We also suggest critical points to be considered for high performance nanostructured HEAs as newborn electrode materials.

Supercapattery: Merging of battery-supercapacitor electrodes for hybrid energy storage devices

Abstract: Supercapattery devices have grasped attention due to their remarkable specific energy (Es) without affecting their specific power (Ps), which is significantly higher compared to batteries and supercapacitors (SCs). In contrast to the traditional electric double layer capacitors (EDLCs) and pseudocapacitors (PCs), supercapattery devices have shown larger specific capacitance. Metal oxides, sulfides, phosphates, and metal-organic frameworks (MOFs) based materials have been extensively utilized for the advancement of hybrid energy storage devices (HESDs). Currently the challenges faced by this technology, is to improve the energy density without compromising the power density. The advantage of two merged technologies (battery and supercapacitor (SC)) into a single system, delivered tremendous power from capacitive components while high specific energy from battery grade material (BGM). This review covers the most recent improvements in vastly used electrode materials, with significant capacity as well as long cyclic life for high-performance supercapattery devices. Furthermore, this study aims to elaborate the electrochemical performance of the metal oxides, sulfides, phosphates, and MOFs for energy storage applications.

Advances in Pseudocapacitive and Battery-like Electrode Materials for High Performance Supercapacitors

Abstract: Supercapacitors (SCs) are energy storage devices with unique characteristics, and together with batteries have generated a significant research effort, with various types of electrode materials been developed over the last...