• Energy Research

AbstractCarbon and transition metals have emerged as promising candidates for many energy storage and conversion devices. They facilitate charge transfer reactions whilst showing a good stability. These materials, fabricated as freestanding electrodes pose the potential of simplified electrode manufacturing procedures whilst demonstrating excellent electrocatalytic, mechanical, and structural properties, resulting from interconnected (via chemical or van der Waals force bonded) network structures. In such freestanding configuration, the lack of a binder leads to a better conductivity, ease in the manufacturing processing, and allows a lower catalyst mass loading, all of which lead to obvious benefits. This Minireview summarizes different fabrication techniques of freestanding non‐precious‐metal oxygen electrocatalysts along with their performance towards the oxygen evolution reaction (OER) and/or oxygen reduction reaction (ORR). Here, we discuss electrocatalysts produced by using freestanding substrates and those obtained through the self‐assembly of different precursors. The advantages of using freestanding versus non‐freestanding configurations are also pondered. Challenges and perspectives for freestanding electrocatalysts are presented at the end of the Minireview as a guideline for future studies in the field. This work is expected to serve as inspiration for science colleagues to develop further studies into design, processing and testing strategies of freestanding low‐cost oxygen electrocatalysts.

The selective electrovalorisation of furfural towards drop-in fuel precursors on single-atom molecular catalysts at ambient conditions via a possible radical coupling pathway.

AbstractPorous carbon materials derived from palm date seeds, guava seeds and winged beans are proposed as environmentally friendly and efficient adsorbents for CO2 and H2S adsorption. The feedstock is converted into hydrochar via hydrothermal carbonization (HTC), at 200°C, for several hours, and the textural properties are tuned using the chemical activation approach with KOH. The activated carbons (ACs) prepared in here are characterized by high surface areas, more than 2000 m2 g‐1, and large pore volumes (1.23 cm3 g‐1). It is observed that a lower concentration of KOH results in a larger number of micropores, leading to improved gas uptake properties. The carbons obtained in here present sponge‐like structure with particle sizes in the range of 5–100 µm. Their morphology is characterized by irregular particle shape with large conchoidal cavities and smooth surfaces. The samples display significant gas adsorption capacity, with 5.47 mmol g‐1 CO2 uptake at 0°C, 1 bar and 4.36 mmol g‐1 at room temperature and atmospheric pressure. H2S adsorption is achieved with more than 50% adsorption efficiency in 1 hour exposure time. Through this study we aim to add up to the eco‐friendly and cost‐effective materials, derived from biomass, suitable and efficient in CO2 and H2S adsorption.

The carbonization of biomass residuals to char has strong potential to become an environmentally sound conversion process for the production of a wide variety of products. In addition to its traditional use for the production of charcoal and other energy vectors, pyrolysis can produce products for environmental, catalytic, electronic and agricultural applications. As an alternative to dry pyrolysis, the wet pyrolysis process, also known as hydrothermal carbonization, opens up the field of potential feedstocks for char production to a range of nontraditional renewable and plentiful wet agricultural residues and municipal wastes. Its chemistry offers huge potential to influence product characteristics on demand, and produce designer carbon materials. Future uses of these hydrochars may range from innovative materials to soil amelioration, nutrient conservation via intelligent waste stream management and the increase of carbon stock in degraded soils.

Different characterization techniques were used to analyse the chemically activated carbons in (i) one dimensional analysis including MIP and BET, (ii) two dimensions including SEM and TEM and (iii) three dimensional X-ray CT. This structure has been directly linked to the electrochemical performance of supercapacitors for the first time.

Lignin in advanced energy applications: source, extraction methodolgy, structure/property relationships.