Facile synthesis of novel molybdenum disulfide decorated banana peel porous carbon electrode for hydrogen evolution reaction

Energy storage and key derives of octadecane thermal stability during phase change assembly with animal manure-derived biochar

The design of eco-friendly and renewable energy infrastructure is highly desirable to advance the global energy landscape. Phase-change materials (PCMs) are used to mitigate intermittency issues and reversibly store high densities of thermal energy in the form of heat during the phase transition process and provide ample potential for the advancement of renewable energy infrastructure. However, the leakage and low thermal stability of pristine PCMs along with the complicated synthesis strategies and environmental issues of the supporting materials cause significant drawbacks, thereby requiring a sustainable confining agent. In this study, a green phase change composite was developed using biowaste-derived biochar and octadecane via a vacuum impregnation strategy. The structural, morphological, thermal, and shape stabilities, as well as the chemical compatibilities of both the composite components and the octadecane-biochar composite, were investigated. The supporting biochar provides sufficient physical and thermal support besides high encapsulating capacity due to high specific surface area (135.2 m2 g-1) and predominant mesoporous proportion (86%). The results displayed that the composite material revealed a high leakage-proof capability (above the melting point of pure octadecane) with a low leakage rate (<12.5%) for a long heating time, excellent thermal stability, and high latent heat retention (89.5%) after 1000 heating-cooling cycles. The fabricated composite attained satisfactory phase change enthalpy storage, which was 130% and 168.9% higher than that of rice-husk-paraffin and garlic peel-derived carbon-paraffin, respectively, indicating promising thermal management performance. This study opens avenues for the development of green composite materials and renewable energy storage and conversion, which will play a significant role in various sectors such as building energy-saving and heat recovery systems.

Promotion of hydrogen evolution from seawater via poly(aniline-co-4-nitroaniline) combined with 3D nickel nanoparticles

This work reports the synthesis of poly (aniline-co-4-nitroaniline) deposited on a three-dimensional nanostructured nickel (3D-Ni) film, where both layers were fabricated via potentiostatic electrodeposition. The obtained electrocatalyst exhibited excellent electrochemical activity for the Hydrogen Evolution Reaction (HER) with small overpotentials of - 195 and - 325 mV at - 10 and - 100 mAcm-2, respectively, and a low Tafel slope of 53.3 mV dec-1 in seawater. Additionally, the electrocatalyst exhibited good stability after 72 h operation under a constant potential of - 1.9 V vs. RHE. The efficient HER performance of the as-prepared catalyst was found to originate from the synergy between the conducting polymer and three-dimensional nickel nanoparticles with a large electrochemical active surface area. Moreover, the results obtained from electrochemical impedance spectroscopy (EIS) measurements revealed that the presence of 3D-Ni layer improved the kinetics of HER by reducing the charge transfer resistance for the electrocatalyst.

Facile and Cost-effective Synthesis of CoP@N-doped Carbon with High Catalytic Performance for Electrochemical Hydrogen Evolution Reaction

The manufacture of efficient and low-cost hydrogen evolution reaction (HER) catalysts is regarded as a critical solution to achieve carbon neutrality. Herein, we developed an economical method to synthesize a CoP-anchored N-doped carbon catalyst via one-step pyrolysis using inexpensive starting materials (cobalt ion salt, phytic acid, and glycine). The size of the CoP nanoparticles was controlled by adjusting the Co/P ratio of the catalysts. Nanoscale CoP particles with adequate exposure to active sites were uniformly anchored on the surface of the conductive nitrogen-doped carbon substrate, ensuring the rapid transfer of electrons and species. When Co/P=0.89, the as-made catalyst exhibited outstanding HER activity, with an extraordinarily low overpotential of 202 mV at 10 mA cm-2 and long-term stability.

Biofabrication of carbon quantum dots and their food packaging applications: a review

Carbon quantum dots (CQDs) are an emerging class of novel carbon nanomaterials (< 10 nm). These zero-dimensional CQDs have recently invoked significant interest due to their high fluorescence ability, strong electronic conductivity, biocompatibility, excellent chemical stability, non-toxicity, and environmental safety. Bio-fabrication of CQDs from organic resources remains attractive owing to their excellent functional properties. An emerging class of CQDs is fabricated by various conventional methods. However, these methods need many chemical agents and instrument facilities. Bio-fabrication of CQDs has a lot of benefits because of its simple fabrication and eco-friendly. Therefore, the green synthesized CQDs are considered optimistic candidates for developing novel functional materials for food packaging applications. Thus, it is important to investigate the latest update on green-based CQDs for food packaging applications. This current review paper discusses the physicochemical properties of CQDs, the bio-fabrication of CQDs, and the fluorescent properties of CQDs along with their food packaging applications.

Facile Synthesis of Functionalized Porous Carbon by Direct Pyrolysis of Anacardium occidentale Nut-Skin Waste and Its Utilization towards Supercapacitors

Preparing electrode materials plays an essential role in the fabrication of high-performance supercapacitors. In general, heteroatom doping in carbon-based electrode materials enhances the electrochemical properties. Herein, nitrogen, oxygen, and sulfur co-doped porous carbon (PC) materials were prepared by direct pyrolysis of Anacardium occidentale (AO) nut-skin waste for high-performance supercapacitor applications. The as-prepared AO-PC material possessed interconnected micropore/mesopore structures and exhibited a high specific surface area of 615 m² g^-1. The Raman spectrum revealed a moderate degree of graphitization of AO-PC materials. These superior properties of the as-prepared AO-PC material help to deliver high specific capacitance. After fabricating the working electrode, the electrochemical performances including cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy measurements were conducted in 1 M H₂SO₄ aqueous solution using a three-electrode configuration for supercapacitor applications. The AO-PC material delivered a high specific capacitance of 193 F g^-1 at a current density of 0.5 A g^-1. The AO-PC material demonstrated <97% capacitance retention even after 10,000 cycles of charge-discharge at the current density of 5 A g^-1. All the above outcomes confirmed that the as-prepared AO-PC from AO nut-skin waste via simple pyrolysis is an ideal electrode material for fabricating high-performance supercapacitors. Moreover, this work provides a cost-effective and environmentally friendly strategy for adding value to biomass waste by a simple pyrolysis route.

Biowaste-Derived Heteroatom-Doped Porous Carbon as a Sustainable Electrocatalyst for Hydrogen Evolution Reaction

Heteroatom-doped porous carbon material (H-PCM) was synthesized using Anacardium occidentale (cashew) nut’s skin by a simple pyrolysis route. The resulting H-PCM was thoroughly characterized by various analytical techniques such as field emission scanning electron microscopy (FE-SEM) with energy-dispersive X-ray (EDX) spectroscopy, high-resolution transmittance electron microscopy (HRTEM), X-ray diffraction (XRD), Raman spectroscopy, nitrogen adsorption–desorption isotherms, X-ray photoelectron spectroscopy (XPS), and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The obtained results strongly demonstrated that the synthesized H-PCM exhibited a porous nature, continuous sponge-like and sheet-like smooth morphology, and a moderate degree of graphitization/crystallinity with oxygen-, nitrogen-, and sulfur-containing functionalities in the carbon matrix. After the structural confirmation, as-prepared H-PCM has used a sustainable electrocatalyst for hydrogen evolution reaction (HER) because the metal-free carbonaceous catalysts are one of the most promising candidates. The H-PCM showed excellent HER activities with a lowest Tafel slope of 75 mV dec−1 and durable stability in 0.5 M H2SO4 aqueous solution. Moreover, this work provides a versatile and effective strategy for designing excellent metal-free electrocatalysts from the cheapest biowaste/biomass for large-scale production of hydrogen gas through electrochemical water splitting.