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This research focuses on the rational design of porous enzymatic electrodes, using horseradish peroxidase (HRP) as a model biocatalyst. Our goal was to identify the main obstacles to maximizing biocatalyst utilization within complex porous structures and to assess the impact of various carbon nanomaterials on electrode performance. We evaluated as-synthesized carbon nanomaterials, such as Carbon Aerogel, Coral Carbon, and Carbon Hollow Spheres, against the commercially available Vulcan XC72 carbon nanomaterial. The 3D electrodes were constructed using gelatin as a binder, which was cross-linked with glutaraldehyde. The bioelectrodes were characterized electrochemically in the absence and presence of 3 mM of hydrogen peroxide. The capacitive behavior observed was in accordance with the BET surface area of the materials under study. The catalytic activity towards hydrogen peroxide reduction was partially linked to the capacitive behavior trend in the absence of hydrogen peroxide. Notably, the Coral Carbon electrode demonstrated large capacitive currents but low catalytic currents, an exception to the observed trend. Microscopic analysis of the electrodes indicated suboptimal gelatin distribution in the Coral Carbon electrode. This study also highlighted the challenges in transferring the preparation procedure from one carbon nanomaterial to another, emphasizing the importance of binder quantity, which appears to depend on particle size and quantity and warrants further studies. Under conditions of the present study, Vulcan XC72 with a catalytic current of ca. 300 µA cm−2 in the presence of 3 mM of hydrogen peroxide was found to be the most optimal biocatalyst support. [ABSTRACT FROM AUTHOR]

Abstract: The production of porous materials together with their associated applications using cheap precursors demonstrates the potential of a “chimie douce” based on carbohydrates and their hydrothermal decomposition products to replace same of the standard organic monomers, fulfilling the today''s requirements towards greener chemistry processes and the sustainability of the starting products. [Copyright &y& Elsevier]

Silica particles containing immobilised peptidic templates have been used for the generation of hierarchically imprinted polymers. The pores of the silica mould were filled with a mixture of monomers/initiator and polymerised, followed by dissolution of the silica template. This method leaves behind imprinted polymers with binding sites located at the surface, which are capable of recognising larger molecules with the same immobilised epitope. All the products resulting from solid-phase synthesis of peptides were characterised by elemental analysis, FT-IR spectroscopy and fluorescence microscopy. The hierarchically imprinted polymers generated from these products were characterised by elemental analysis, FT-IR spectroscopy, fluorescence microscopy, scanning electron microscopy (SEM) and nitrogen adsorption, providing evidence concerning the reproducibility of each step. The chromatographic properties of the materials have been investigated and the advantages of the immobilisation method have been proven. The materials exhibit selectivity for their templates and other structurally related dipeptides. Furthermore, the polymers proved to be capable of recognising larger peptides containing the immobilised sequence. [ABSTRACT FROM AUTHOR]

The next generation of proton exchange membrane fuel cells (PEMFCs) require a substantial reduction or elimination of Pt-based electrocatalyst from the cathode, where O 2 reduction takes place. The most promising alternative to Pt is atomic Fe embedded in N-doped C (Fe–N–C). Successful incorporation of Fe–N–C in PEMFCs relies on a thorough understanding of the catalyst layer properties, both ex situ and in situ , with tailored electrode interface engineering. To help resolve this conundrum, we provide a quantitative protocol on the optimisation of I/C for Fe–N–Cs. It is demonstrated that a high pore volume (3.33 cm3 g−1 FeNC) Fe–N–C catalyst requires a sufficiently high ionomer to catalyst mass ratio (I/C, 2.8≤I/C ≤ 4.2) for optimum PEMFC activity under H 2 /O 2. Emerging electrochemical techniques (distribution of relaxation times and Fourier transformed alternating current voltammetry) were used to deconvolute for the first time the trade-off between proton and electron resistance and accessible FeN x active site density with increasing ionomer loading. These findings highlight the significant impact of tuning the I/C ratio based on the catalyst layer properties and feature the power of evolving electrochemical tools for optimising performance in PEMFCs and other electrochemical devices. [Display omitted] • In situ FTacV quantified Fe–N–C electrochemical active site density in fuel cell. • Fe–N–C active site density and current density correlated with ionomer loading. • DRT quantified resistance to proton transport and oxygen diffusion in fuel cell. • Fe–N–C to ionomer ratio optimised based on quantitative protocol. [ABSTRACT FROM AUTHOR]

Hard carbons (HCs) are a significantly promising anode material for alkali metal-ion batteries. However, long calcination time and much energy consumption are required for the traditional fabrication way, resulting in an obstacle for high-throughput synthesis and structure regulation of HCs. Herein, we report an emerging sintering method to rapidly fabricate HCs from different carbon precursors at an ultrafast heating rate (300 to 500 °C min-1) under one minute by a multifield-regulated spark plasma sintering (SPS) technology. HCs prepared via the SPS possess significantly fewer defects, lower porosity, and less oxygen content than those pyrolyzed in traditional sintering ways. The molecular dynamics simulations are employed to elucidate the mechanism of the remarkably accelerated pyrolysis from the quickly increased carbon sp² content under the multifield effect. As a proof of concept, the SPSderived HC exhibits an improved initial Coulombic efficiency (88.9%), a larger reversible capacity (299.4 mAh⋅g-1), and remarkably enhanced rate capacities (136.6 mAh⋅g-1 at 5 A⋅g-1) than anode materials derived from a traditional route for Na-ion batteries. [ABSTRACT FROM AUTHOR]

Accurate modelling of particle shrinkage during biomass pyrolysis is key to the production of biochars with specific morphologies. Such biochars represent sustainable solutions to a variety of adsorption-dependent environmental remediation challenges. Modelling of particle shrinkage during biomass pyrolysis has heretofore been based solely on theory and ex-situ experimental data. Here we present the first in-situ phase-contrast X-ray imaging study of biomass pyrolysis. A novel reactor was developed to enable operando synchrotron radiography of fixed beds of pyrolysing biomass. Almond shell particles experienced more bulk shrinkage and less change in porosity than did walnut shell particles during pyrolysis, despite their similar composition. Alkaline pretreatment was found to reduce this difference in feedstock behaviour. Ex-situ synchrotron X-ray microtomography was performed to study the effects of pyrolysis on pore morphology. Pyrolysis led to a redistribution of pores away from particle surfaces, meaning newly formed surface area may be less accessible to adsorbates. [ABSTRACT FROM AUTHOR]

Anisotropic, biomorphic (wood-derived) potassium-based geopolymer (KGP) - biocarbon (C B ) composites with net shape were manufactured by infiltrating KGP slurry into monolithic porous biocarbon (C B ) structures (~77 vol% porosity) derived from pyrolyzing beech wood. About 70% of the pores in the three-dimensional (3D) C B structures were infiltrated by the KGP slurry. Compared to pure KGP, the energy absorption per unit volume in compression loading of the KGP-C B composites was increased by ten-fold. After heat treatment at 1000 °C for 1 h in N 2 , the compressive strength of the KGP-C B composites increased from ~7–24 MPa, accompanied by the formation of crystalline leucite (K 2 O·Al 2 O 3 ·4SiO 2 ) phase in the KGP. The KGP-C B composite also exhibited three orders higher electrical conductivity than pure KGP. The effect of temperature on the formation of crystalline phases in KGP and KGP-C B composites was investigated. FTIR, TGA and SEM analyses were used to investigate the changes in microstructures and phase formation during thermal treatment. [ABSTRACT FROM AUTHOR]

Dye sensitized solar cells have emerged as an attractive alternative to conventional solar cells due to their easy processing and the abundance and low cost of their materials. However, the counter electrode in these cells employs platinum which significantly impacts their cost. Here, we report biomass-derived, nitrogen-doped carbon aerogel as an effective alternative to conventional platinum-based counter electrodes for dye sensitized solar cells. A stable suspension of biomass-derived, nitrogen-doped carbon aerogel was prepared in DMF by using oleylamine as a binder. The nitrogen-doped carbon aerogel electrode was annealed at different temperatures, and its impact on photovoltaic performance is investigated. I-V measurements confirm that the annealing temperature substantially enhances the photovoltaic parameters of these devices; these enhancements are linked to the removal of the organic binders. Electrochemical impedance spectra of the counter electrodes confirm that removal of oleylamine in nitrogen-doped carbon aerogels reduces the series resistance of the resulting electrodes. The power conversion efficiency of the solar cells from optimized nitrogen-doped carbon aerogel exhibited comparable efficiency to that of a cell fabricated using a platinum-based counter electrode. This study demonstrates the potential of biomass-derived carbon aerogels as a cheap and sustainable replacement of platinum in DSSCs. [ABSTRACT FROM AUTHOR]

Developing the low-cost, highly active carbonaceous materials for oxygen reduction reaction (ORR) catalysts has been a high-priority research direction for durable fuel cells. In this paper, two novel N-doped carbonaceous materials with flaky and rod-like morphology using the natural halloysite as template are obtained from urea nitrogen source as well as glucose (denoted as GU) and furfural (denoted as FU) carbon precursors, respectively, which can be directly applied as metal-free electrocatalysts for ORR in alkaline electrolyte. Importantly, compared with a benchmark Pt/C (20wt%) catalyst, the as-prepared carbon catalysts demonstrate higher retention in diffusion limiting current density (after 3000 cycles) and enhanced methanol tolerances with only 50-60mV negative shift in half-wave potentials. In addition, electrocatalytic activity, durability and methanol tolerant capability of the two N-doped carbon catalysts are systematically evaluated, and the underneath reasons of the outperformance of rod-like catalysts over the flaky are revealed. At last, the produced carbonaceous catalysts are also used as cathodes in the single cell H 2 /O 2 anion exchange membrane fuel cell (AEMFC), in which the rod-like FU delivers a peak power density as high as 703 mW cm −2 ( vs. 1106 mW cm −2 with a Pt/C benchmark cathode catalyst). [ABSTRACT FROM AUTHOR]

[Display omitted] • Battery-grade graphite was fabricated in 13 min at a low temperature of 1100 °C. • Fast carbonation is achieved by a multi-physics field carbonization coupling with a Ni catalyst. • Molecular dynamics revealed the exceptional kinetics carbonization by MPF. • The obtained graphite anode provides a reversible Li+ storage capacity of 370.7 mAh g−1. • The graphite anode delivers long cycling life over 10,000 cycles at 2 A g−1 in diglyme-based Na-ion batteries. The typical synthesis of graphite requires carbonization at 2800 °C, which consumes a substantial amount of energy. We present a novel, sustainable and cost-effective method for synthesizing high-crystallinity graphite in 13 min at a low temperature of 1100 °C and a multi-physics field (MPF) carbonization coupling with a Ni catalyst. The MPF synergistically benefits from a thermal field, an electric field, and a pressure field in an MPF furnace at the lab scale. Molecular dynamics and differential charge density calculation indicated that the MPF carbonization facilitated exceptional kinetics, and considerably accelerated the breaking of the Ni-metal-catalyzed C-O bonds. The starch-derived graphite anode provided a reversible Li+ storage capacity of 370.7 mAh g−1, matching that of commercial graphite. It also demonstrates exceptional rate performance with a capacity of 103.3 mAh g−1 at an ultra-high current density of 30 A g−1 in diglyme-based Na-ion batteries and ultrastable cycling performance over 10,000 cycles at 2 A g−1. This method will shed some light on how to rapidly fabricate highly crystalline graphite by a energy-saving and low-cost route. [ABSTRACT FROM AUTHOR]

Sustainable and green manufacturing of hard carbon (HC) material in a low-cost way is the key issue in promoting its industrial applications in Na-ion batteries (SIB). Nowadays, most synthesis ways to prepare HC need the help of chemical reagents to improve its Na-ion storage performance. Herein, we firstly developed a completely green biological fermentation technology to prepare HCs on a large scale using cheap and renewable carbon sources of various biomass starch. Pre-treatment by bio-fermentation can effectively modify the carbon precursor for facile pyrolysis to fabricate starch-based HCs, and make its internal microstructure with larger interlayer spacing, more disordered structure and abundant closed micropores. Finally, a case of cornstarch-based hard carbon exhibits a high reversible capacity of 335 mA h g−1 at a current density of 30 mA h g−1 and high rate performance with a reversible capacity of 140.6 mA h g−1 even at a high current of 5 A g−1 as well as long cycling stability. In-situ Raman spectra, ex-situ SAXS and ex-situ XPS tests during discharge and charge process reveal the pore filling mechanism of quasi-metallic Na in hard carbon anode. Such a "bread-making"strategy is a facile and scalable route to fabricate various starch-based hard carbons with improved performance, demonstrating a very practically promising application for industrial manufacture. • A green biological fermentation technology to prepare HCs is firstly developed. • Renewable carbon sources of various biomass starch derived HCs are achieved. • Bio-fermentation effectively improve interlayer spacing with abundant closed micropores. • HC with a reversible capacity of 335 mA h g−1 and long cycling stability is demonstrated. • Such a "bread-making" strategy is a scalable route to fabricate hard carbons at a kilogram. [ABSTRACT FROM AUTHOR]

This paper reports an "all in one" procedure to produce mesoporous, micro-spherical LiFePO4 composed of agglomerated crystalline nanoparticles. Each nanoparticle is individually coated with a thin glucose-derived carbon layer. The main advantage of the as-synthesized materials is their good performance at high charge-discharge rates. The nanoparticles and the mesoporosity guarantee a short bulk diffusion distance for both lithium ions and electrons, as well as additional active sites for the charge transfer reactions. At the same time, the thin interconnected carbon coating provides a conductive framework capable of delivering electrons to the nanostructured LiFePO4. [ABSTRACT FROM AUTHOR]

Abstract: Photodegradation of methylene blue on a carbon-doped TiO2 and on pure TiO2 was studied. The materials were prepared by solvothermal synthesis and by calcinations. N2 adsorption, XRD, SEM and TEM characterization was performed. Both nanomaterials exhibited mesoporous textures and the TiO2 frameworks consist mainly of anatase phase. SEM images showed spherical microparticles while the TEM images showed hierarchically nanostructured morphologies on both samples. C-TiO2 exhibited higher apparent first-order rate constants for the degradation of methylene blue than those obtained on pure TiO2. It could be concluded that under visible light, the photoactivity of carbon-doped TiO2 was clearly higher than that of a commercial TiO2 photocatalyst suggesting that the carbon part photo assist the TiO2 in the photodegradation of methylene blue. [ABSTRACT FROM AUTHOR]

Abstract: Greenhouse gas mitigation options include the production of carbonized materials and their addition to soils for longer term storage. Hydrothermal carbonization (HTC) is a novel way to produce carbonized materials. The goal here was to test if HTC material, in our case derived from beet root chips, has adverse effects on plant growth or that of root associated symbionts such as arbuscular mycorrhizal fungi. We carried out several studies, and found that increasing concentrations of HTC material could be deleterious for plant growth of Taraxacum, starting at 10vol% additions. Conversely, root colonization of the fungal symbiont was stimulated at an addition of 20vol%. Soil pH changes occurring during the study could be traced to microbial reduction reactions, and these led to a pH increase of the medium despite the quite acidic nature of the HTC material itself. In separate assays, we showed that spore germination of the AM fungus Glomus intraradices was stimulated by the HTC material, suggesting that direct effects on the fungi are likely in addition to those mediated by the host plant. A third experiment with a different plant species (Trifolium repens) confirmed the major conclusions, and showed also neutral to stimulatory effect on nodulation. Our results suggest that HTC materials should be carefully tested and optimized to reduce negative effects on plant growth before applications in the field are undertaken, particularly at high addition rates. [Copyright &y& Elsevier]

Abstract: We describe the production and catalytic application of highly functionalized mesoporous carbonaceous materials, obtained via a one step green and cheap process relying on the hydrothermal carbonization of carbohydrates (e.g. glucose) in the presence of functional organic monomers (e.g. vinyl imidazole). The resulting materials could be further functionalized to feature imidazolium bromides on their surface and be used for various transesterification, Knoevenagel and Aldol reactions. [Copyright &y& Elsevier]

Photoelectrochemical imaging has great potential in the label-free investigation of cellular processes. Herein, we report a new fast photoelectrochemical imaging system (PEIS) for DC photocurrent imaging of live cells, which combines high speed with excellent lateral resolution and high photocurrent stability, which are all crucial for studying dynamic cellular processes. An analog micromirror was adopted to raster the sensor substrate, enabling high-speed imaging. α-Fe 2 O 3 (hematite) thin films synthesized via electrodeposition were used as a robust substrate with high photocurrent and good spatial resolution. The capabilities of this system were demonstrated by monitoring cell responses to permeabilization with Triton X-100. The ability to carry out dynamic functional imaging of multiple cells simultaneously provides improved confidence in the data than could be achieved with the slower electrochemical single-cell imaging techniques described previously. When monitoring pH changes, the PEIS can achieve frame rates of 8 frames per second. [Display omitted] • Photoelectrochemical imaging setup with high spatiotemporal resolution developed. • Fast, high-resolution pH imaging at a rate of 8 frames per second. • Real-time live-cell imaging of permeabilization of cell membranes with surfactant. • Biocompatible and stable hematite substrate as sensor chip for live cell imaging. [ABSTRACT FROM AUTHOR]

We successfully construct noble-metal-free cobalt nitride/nitrogen-rich carbons (Co 4 N/NCs) catalysts by a photochemical assembly strategy. The obtained Co 4 N/NCs catalysts show extraordinary activity for CO 2 -to-CO reduction. The highest turnover frequency per cobalt atom within Co 4 N/NCs reaches 6.7 s-1. • Cobalt nitride/nitrogen-rich carbons (Co 4 N/NCs) are prepared by a photochemical approach. • The Co 4 N/NCs is an effective catalyst for CO 2 reduction. • The quantum yield for CO production over the Co 4 N/NCs reaches 7.2% at 450 nm. Utilizing solar energy to convert CO 2 into fuels and chemicals represents a promising solution to reduce reliance on fossil fuels, but it is hampered by the lack of highly-efficient catalysts. Herein, we report unique cobalt nitride/nitrogen-rich carbons (Co 4 N/NCs), which can work as noble-metal-free catalysts for CO 2 -to-CO conversion. The mass activity of Co 4 N/NCs is two orders of magnitude higher than those of previously reported CO 2 photoreduction catalysts. The quantum yield for CO production at 450 nm reaches 7.2% with a turnover frequency per Co atom of 0.97 s-1. The electronic structure and coordinated environment of catalysts are analyzed by X-ray absorption fine structure spectroscopy and X-ray photoelectron spectroscopy. The reaction processes are investigated by in-situ diffuse reflectance infrared fourier transform spectroscopy and density functional theory calculations. Results suggest that the synergetic effects between the Co 4 N and the NCs can consolidate the adsorption and activation of CO 2 and accelerate the interfacial electron-transfer kinetics between the Co 4 N/NCs catalysts and light-harvesting antenna, thereby resulting in the outstanding activity for synthesizing CO from CO 2. This work offers the possibility to design Co-based host-guest topology for highly-efficient CO 2 reduction. [ABSTRACT FROM AUTHOR]

The growing importance of bio-based products, combined with the desire to decrease the production of wastes, boosts the necessity to use wastes as raw materials for bio-based products. A waste material with a large potential is spent sugar beets, which are mainly used as animal feeds or fertilizers. After hydrothermal treatment, the produced chars exhibited an H/C ratio of 1.2 and a higher heating value of 22.7 MJ/kg, which were similar to that of subbituminous coal and higher than that of lignite. Moreover, the treatment of 25 g/L of glucose and 22 g/L of fructose by heating up to 160 °C led to a possible application of spent sugar beets for the production of 5-hydroxymethylfurfural. In the present study, the maximum concentration of 5-hydroxymethylfurfural was 3.4 g/L after heating up to 200 °C. [ABSTRACT FROM AUTHOR]

Brewer's spent grains (BSG) represent a highly abundant byproduct generated in the beer industry. Owing to abundant availability and high water content, BSG constitutes a raw material of interest for thermochemical conversion via hydrothermal carbonization (HTC). Nevertheless, the phyto-toxic effect and low-porosity of hydrochars limit the possible application. Therefore, coupling HTC and pyrolysis may overcome these obstacles. HTC experiments were carried out at 180, 220, and 260 °C and pyrolysis was performed at 400, 600, 800, and 1000 °C to investigate the influence of HTC on the pyrolysis of BSG. Pyrolyzed hydrochars showed lower ash content and higher carbon content compared to char obtained from BSG. The highest surface area (139.5 m2 g−1) was obtained for hydrochar produced at 180 °C and then pyrolyzed at 600 °C. This value was 70% higher compared to BSG pyrolyzed at the same temperature (82 m2 g−1). The coupling of HTC and pyrolysis showed synergies in the char yield, reduction of ash, increasing of carbon content, and porosity. The promising results proved that at selected process conditions, the novel route is beneficial for carbon materials production due to the improvement of the physicochemical properties of pyrochar at similar mass and carbon yields. Image 1 • One-step pyrolysis and two-step HTC coupled with pyrolysis was investigated. • Low-temperature HTC in two-step process resulted in similar char yield as pyrolysis. • Coupling of HTC and pyrolysis improved physicochemical properties of pyrochars. • Highest S BET was achieved for hydrochar obtained at 180 °C and pyrolyzed at 600 °C. [ABSTRACT FROM AUTHOR]

The aim of this work was to test activated carbons derived from hydrochars produced from sunflower stem, olive stone and walnut shells, as adsorbents for emerging contaminants in aqueous solution, namely fluoxetine and nicotinic acid. The adsorption capacity was determined by the chemical nature of the adsorbents, namely the presence of specific functional groups and their positive or negative ionization in aqueous solutions and also by steric factors. The activated carbons produced by air showed a higher adsorption capacity of fluoxetine, whilst the samples produced by carbon dioxide activation were more useful to remove nicotinic acid. In general, surface acidity was advantageous for fluoxetine adsorption and detrimental for nicotinic acid removal. The adsorption mechanisms involved in each case were discussed and related to the adsorbents characteristics. The maximum adsorption capacity, Q0, given by the Langmuir model was 44.1 and 91.9 mg g−1 for fluoxetine and nicotinic acid adsorption, respectively. [ABSTRACT FROM AUTHOR]

The nitrogen vacancies on the carbon nitride surface can function as active sites to catalyze water oxidation reaction, while preventing recombination of the electron/hole pairs, thus accelerating the reaction kinetic of oxygen photosynthesis. • A photocarving strategy is first employed to create nitrogen vacancies (NVs) on the surface of polymeric carbon nitride (PCN). • The embedded NVs can function as active sites to catalyze oxygen evolution reaction (OER), thereby accelerating the sluggish kinetic of OER. • The embedded NVs can effectively promote the separation and transfer of the photogenerated charge carrier. • The PCN-NVs without any extra metal cocatalyst assistance exhibits a 4.2-fold increase in the oxygen photosynthesis activity compared with pristine PCN. Photocatalytic water splitting necessitates robust cocatalysts to accelerate the oxygen evolution reaction (OER). However, most OER cocatalysts are based on noble metal oxides. Besides, the loose interface between semiconductor and cocatalyst results in inefficient charge transfer. The fabrication of photocatalysts with integrated light-harvesting and catalytic centers for OER is therefore desired. Herein, we provide a photocarving strategy to create nitrogen vacancies (NVs) on polymeric carbon nitride (PCN). It is confirmed that the embedded NVs can function as active sites to catalyze OER, while promoting the transfer of the photogenerated charge for OER. As a result, PCN-NVs without any extra noble-metal cocatalyst assistance exhibit an enhanced oxygen evolution rate compared with the pristine PCN. Additionally, the PCN obtained from other precursors can also be engineered by this photocarving method, while promoting oxygen photosynthesis. This work provides an avenue to design light-transducers with combined light-harvesting and catalytic configurations for oxygen synthesis chemistry. [ABSTRACT FROM AUTHOR]