Biomass-derived Activated Carbon Research Articles

Physical activation assisted porous activated carbon from Strychnos Potatorum shells for high-performance symmetric supercapacitors

Herein, low-cost activated carbon (AC) prepared from Strychnos Potatorum shells using CO2 as an activating agent via physical activation technique. Waste biomass-derived AC have the merits of excellent conductivity and highly porous with high-surface area. Electrochemical assessments indicated that the prepared Strychnos Potatorum derived activated carbon (SPAC) electrode exhibited superior electrochemical performance. The experimental data showed that the specific capacitance of 352.5 F g−1 at 0.5 A g−1 and retained 140 F g−1 at 20 A g−1. Symmetric supercapacitors SPAC//SPAC device displayed an impressive specific capacitance of 147 F g−1 at 0.1 A g−1 and an energy density of 20.41 W h kg−1 at 100 W kg−1 and retained 2.7 Wh kg−1 at 10000 W kg−1. Furthermore, these supercapacitors demonstrated exceptional cyclability, maintaining capacity retention of 92.3 % over 10,000 charge–discharge cycles at 1 A g−1. This research work underscores the promising potential of AC materials derived from Strychnos Potatorum shells in development of high-performance supercapacitors.

Hydrophobic modification of walnut shell biomass-derived porous carbon for the adsorption of VOCs at high humidity

Volatile organic compounds (VOCs) often contain water vapor in their exhaust emissions, resulting in the deterioration of the adsorption capacity of activated carbon (AC). A hydrophobic walnut shell biomass-derived AC using polytetrafluoroethylene (PTFE) and polydimethylsiloxane-coated SiO2 (PDMS/SiO2) was developed to improve the selectivity of VOCs under high humidity conditions. These modified ACs were systematically characterized, and dynamic adsorption behaviors of VOCs such as toluene, acetone and their mixtures at the relative humidity (RH) between 0 and 90 % were conducted. The results showed that walnut shell biomass-derived AC has large specific surface area (1853 m2/g) and total pore volume (1.27 cm3/g), strong hydrophilicity (water contact angle of 6.3°), abundant oxygen-containing groups (OH, CO, CO) and aromatic rings. The coating of PDMS/SiO2-PTFE reduces the surface area and total pore volume of AC, but it creates a double-layer rough structure on the AC surface and introduces CF and SiOSi hydrophobic groups, which achieves a water contact angle of 152.8° for 25PSP/AC. The Yoon-Nelson model is suitable to describe the dynamic adsorption process of single- toluene or acetone under dry/humid condition but not suitable for their mixtures. At RH 90 %, PDMS/SiO2-PTFE modified AC significantly increases the adsorption capacity of toluene but is not obviously improved for acetone, which is due to the different polarity of toluene and acetone. PDMS/SiO2-PTFE films on AC have good thermal stability before 500 °C and the hydrophobicity does not change after multi-regeneration at 200 °C. Therefore, PDMS/SiO2-PTFE modified AC has shown great potential as adsorbent to remove the toluene from the humid condition.

Exploring the insights and benefits of biomass-derived sulfuric acid activated carbon for selective recovery of gold from simulated waste streams

The surging affluent in society, concomitant with increasing global demand for electrical and electronic devices, has led to a sharp rise in e-waste generation. E-wastes contain significant amounts of precious metals, such as gold, which can be recovered and reused, thus reducing the environmental impact of mining new metals. Selective recovery using sustainable and cost-effective materials and methods is therefore vital. This study undertook a detailed evaluation of low-cost biomass-derived activated carbon (AC) for selective recovery of Au from simulated e-waste streams. Utilizing high-performance synthesized H2SO4-AC, the adsorption mechanisms were explicated through a combination of characterization techniques, i.e., FE-SEM, BET, TGA, XRD, FTIR, XPS, and DFT simulations to conceptualize the atomic and molecular level interactions. Optimization of coordination geometries between model H2SO4-AC and anionic complexes revealed the most stable coordination for AuCl4- (binding energy, Eb = -4064.15 eV). The Au selectivity was further enhanced by reduction of Au(III) to Au(0), as determined by XRD and XPS. The adsorption reaction was relatively fast (∼5h), and maximum Au uptake reached 1679.74 ± 37.66 mg/g (among highest), achieved through adsorption isotherm experiments. Furthermore, a mixture of 0.5 M thiourea/1 M HCl could effectively elute the loaded Au and regenerate the spent AC. This study presents radical attempts to examine in detail, the synergistic effects of H2SO4 activation on biomass-derived ACs for selective recovery of Au from complex mixtures. The paper therefore describes a novel approach for the selective recovery of Au from e-wastes using multifunctional biomass-derived H2SO4-AC.

Fluidity comparison of biomass-derived activated carbon and TiO(OH)2 and its improving toward promoted low-temperature CO2 capture in gaseous medium

Biowaste-derived activated carbons (ACs) and TiO(OH)2 are considered promising materials for effective CO2 capture. TiO(OH)2 has not been employed in gas phase adsorption process; moreover, the comparison of fluidization of these materials had not been investigated. Hence, this study not only did evaluate the CO2 adsorption performance of both synthetic TiO(OH)2 and biomass-derived AC, but also assessed their fluidity aimed to implement at pilot scales. The samples were examined using XRD, BET, SEM, EDX, FTIR, and TGA techniques. The adsorption of the adsorbents was evaluated through TGA under several conditions. The AC demonstrated an average CO2 capture capacity of 3.54 mmol/g, surpassing that of the TiO(OH)2 (0.971 mmol/g) during three successive cycles at 25/120 ℃ under a CO2/N2 flow of 90/10 vol% and 1 bar. Adding 5 wt% of auxiliary SiO2 nanoparticles enhanced bed expansion of AC and TiO(OH)2 by 1.83 and 1.5 times respectively, due to dwindling interparticle cohesive interactions.

Advancements in Biomass-Derived Activated Carbon for Sustainable Hydrogen Storage: A Comprehensive Review.

The increasing global energy demand, which is being driven by population growth and urbanization, necessitates the exploration of sustainable energy sources. While traditional energy generation predominantly relies on fossil fuels, it also contributes to alarming CO2 emissions. Hydrogen has emerged as a promising alternative energy carrier with its zero-carbon emission profile. However, effective hydrogen storage remains a challenge. When exposed to hydrogen, conventional metallic vessels, once considered to be the primary hydrogen carriers, are prone to brittleness-induced cracking. This has spurred interest in alternative storage solutions, particularly porous materials like metal-organic frameworks and activated carbon (AC). Among these, biomass-derived AC stands out for its eco-friendly nature, cost-effectiveness, and optimal adsorption properties. This review offers a comprehensive overview of recent advancements in the synthesis, characterization, and hydrogen storage capabilities of AC. The unique benefits of biomass-derived sources are highlighted, as is the pivotal role of chemical and physical activation processes. Furthermore, we identify existing challenges and propose future research directions in AC-based hydrogen storage. This compilation aims to serve as a foundation for potential innovations in sustainable hydrogen storage solutions.

Corn-straw-converted activated carbons with tunable porosity and N/O functionalities as high-performance supercapacitors electrode at commercial-level mass loading

With the scientific importance and industrial need for low-cost but high-performance activated carbons (ACs) for supercapacitors (SCs), ACs with tailorable porous texture and heteroatom doping are turned from corn straw via hydrothermal and activation processes. Porous texture is mainly adjusted by KOH/biochar mass ratio. O and N surface functionalities are tuned by a subsequent high-temperature treatment by H2O or ammonia. The influences of porosity in the amounts of the introduced N contents are investigated. With symmetric SC cells, the electrochemical performances of the corn-straw-derived ACs are examined at commercial-level mass loading. For aqueous electrolyte, the ACs prepared without KOH activation but with high-temperature treatment by ammonia exhibit high gravimetric capacitance of 192 F/g and volumetric capacitance of 150 F/cm3 due to their high compact density and N atomic fraction. For organic system, the optimum ACs are activated with KOH/biochar ratio of 1:1 and a subsequent ammonia high-temperature treatment, which deliver high gravimetric capacitance of 258 F/g and volumetric capacitance of 167 F/cm3. Balanced porosity and density, low O fraction but high N fraction are found to be favored for organic system. The cost-effective technique route may provide guidance for the design and preparation of biomass-derived ACs with tunable porosity and heteroatom functionalities for practical applications in SCs.

Promoted wet peroxide oxidation of chlorinated volatile organic compounds catalyzed by FeOCl supported on macro-microporous biomass-derived activated carbon

Chlorinated volatile organic compounds (CVOCs) are a recalcitrant class of air pollutants, and the strongly oxidizing reactive oxygen species (ROS) generated in advanced oxidation processes (AOPs) are promising to degrade them. In this study, a FeOCl-loaded biomass-derived activated carbon (BAC) has been used as an adsorbent for accumulating CVOCs and catalyst for activating H2O2 to construct a wet scrubber for the removal of airborne CVOCs. In addition to well-developed micropores, the BAC has macropores mimicking those of biostructures, which allows CVOCs to diffuse easily to its adsorption sites and catalytic sites. Probe experiments have revealed HO• to be the dominant ROS in the FeOCl/BAC + H2O2 system. The wet scrubber performs well at pH 3 and H2O2 concentrations as low as a few mM. It is capable of removing over 90% of dichloroethane, trichloroethylene, dichloromethane and chlorobenzene from air. By applying pulsed dosing or continuous dosing to replenish H2O2 to maintain its appropriate concentration, the system achieves good long-term efficiency. A dichloroethane degradation pathway is proposed based on the analysis of intermediates. This work may provide inspiration for the design of catalyst exploiting the inherent structure of biomass for catalytic wet oxidation of CVOCs or other contaminants.

Non-precious metal catalysts supported by activated carbon and TiO2–SiO2: Facile preparation and application for highly effective hydrodeoxygenation of syringol–a lignin-derived model compound

Non-precious metal catalysts (10 wt% loading) over activated carbon (AC) and TiO2–SiO2 supports prepared via incipient wetness impregnation and spray pyrolysis were characterized using various analytical techniques. AC with a higher surface area displayed a better ability than TiO2–SiO2 in syringol conversion and hydrocarbon product selectivity. Compared to Fe and NiFe catalysts, the Ni catalyst showed more effective hydrodeoxygenation performance in terms of syringol conversion, selectivity, and the yield of oxygen-free products (mainly alkylbenzenes via transalkylation reactions). The deoxygenation ability was confirmed via the moisture and COx release. The highest syringol conversion (99.91%) could be obtained using 10 wt% Ni/AC. Generally, syringol hydrodeoxygenation in a fixed-bed reactor followed the main reaction pathway of the hydrogenolysis of CAr–OC(sp3) and CAr–OH rather than the hydrogenation of the benzene ring, producing p-xylene, phenol, and cresols as the major products. Besides metallic catalysts and supports, the reaction temperature and the total flow rate of the H2/Ar mixture on hydrodeoxygenation performance were also investigated. Our study provides a promising potential in the utilization of non-precious metals and biomass-derived AC to remove oxygen from bio-oil model compounds, contributing to the development of sustainable renewable energy.

Bamboo-derived hydrophobic porous graphitized carbon for adsorption of volatile organic compounds

Biomass-derived activated carbons (BACs) are often used as green adsorbents for the removal of VOCs, however, their abundant surface functional groups severely reduced their adsorption selectivity under humid conditions. In this study, hydrophobic bamboo-derived porous graphitized carbons (BPGCs) were prepared using a combined catalytic graphitization method. The optimal micro-mesoporous BPGC had a large specific surface area of 2181 m2/g and a low surface O/C ratio of 0.038. Under dry conditions, its adsorption capacities for toluene, cyclohexane and ethanol were 6.7, 3.8 and 2.4 mmol/g, respectively. At 80 % relative humidity, its adsorption capacities for toluene and cyclohexane remained 82 % and 66 %, while the uptake of ethanol even increased by 33 %. In the two-component adsorption test, BPGC showed a high selectivity for toluene adsorption over ethanol, with 198 times more toluene than ethanol. The adsorption mechanism at the microscopic molecular level was revealed by DFT calculation. The abundant π electrons and high polarizability of BPGC allow for strong π-π interactions and dispersion forces with non-polar organics, while the abundant oxygen-containing groups on BAC have strong adsorption force on water. The absorption of ethanol by capillary condensed water in mesopores of BPGC may contribute to its increased uptake under humid conditions. BPGC allowed for faster adsorption kinetics than activated carbon. More than 90 % of the adsorbed toluene was desorbed from BPGC at 90 °C. Owing to abundant renewable raw materials, excellent hydrophobicity and desirable textural properties, BPGCs may be promising adsorbents.

Facile one-pot synthesis of biomass-derived activated carbon as an interlayer material for a BAC/PE/Al2O3 dual coated separator in Li-S batteries.

Lithium-sulfur batteries (LSB) are an attractive alternative electrochemical energy storage device compared to conventional lithium-ion batteries due to their higher theoretical capacity and energy density. Despite these advantages, it is still difficult to commercialize LSB because of poor electrochemical performance caused by the dissolution of soluble lithium polysulfides (LiPS). To solve these critical issues, a multi-functional separator was prepared using biomass-derived activated carbon (BAC) and a ceramic layer on the polyethylene (PE) separator. For this purpose, BAC was synthesized by a facile one-pot synthesis method by a specifically designed furnace using various forms of milk waste. The multi-functional separator suppresses the effect of LiPS dissolution and increases the Li+ diffusion kinetics. BAC was able to absorb the LiPS shuttle, as confirmed by UV-vis measurements and X-ray photoelectron spectroscopy (XPS). LSB cells assembled using this multi-functional separator show a higher discharge capacity of 1092.5 mA h g-1 at 0.1 C-rate, while commercial PE separators deliver a specific capacity of 811.8 mA h g-1. These novel separators were also able to suppress lithium dendrites during cycling. This work offers a novel and simple approach for streamlining the synthesis process of BAC and applying it to LSB, aiding in the development of sustainable energy sources.

Algal biomass-derived nano-activated carbon for the rapid removal of tetracycline by adsorption: Experimentation and adaptive neuro-fuzzy inference system modeling

Tetracycline (TC) is one of the antibiotics, which is detected at high titre in aquatic systems, inducing microbial resistance. This study highlights the adsorptive removal of TC by activated carbon (AC) using low temperature carbonization obtained from Ulva prolifera macroalgal biomass – an abundantly available algae in southern Indian beaches. The AC had rough, irregular, and porous structure with large specific surface area of 197.53 m2/g. The adsorption data was modelled using adaptive neuro-fuzzy inference system that fitted the data satisfactorily. Pseudo-second-order kinetics well-suited TC adsorption confirming to chemisorption. Both Langmuir and Freundlich isotherms suited-well to the data with monolayer adsorption capacity of 54.04 mg/g, which emphasized the suitability of using the algal biomass-derived AC for TC removal over other adsorbents. Therefore, the present investigation highlights the use of a new low-cost nanoadsorbent developed from algal biomass along with the tremendous potential of ANFIS in predicting the adsorption process.

High-performance moisture-diffusion energy harvester using catalytic activated carbon derived from biomass

Biomass-derived activated carbon (Bio-AC) was prepared by catalytic activation of corn stover followed by milling and surface modification. The prepared Bio-AC was coated onto a fibrous material to fabricate the biomass-derived moisture diffusion energy harvester (Bio-MDEH), which generates electricity from the flow of ions in moisture that diffuse along the interface of conductive carbon particles. The performance of this device was evaluated by measuring open-circuit voltage (Voc) and short-circuit current (Isc). The maximum performance of 926.2 mV and 37.75 μA, which is 4.6-fold of carbon black MDEH, was achieved using KOH-catalyzed activated carbon. Development of mesopore structure, introduction of hydrophilicity, and improvement of electrical conductivity induced from catalytic activation contributed to the improvement of MDEH performance. Several Bio-MDEHs connected in series or parallel reliably generated 1.8 V and 214 μA of electricity and successfully lit a single light-emitting diode. A Bio-MDEH conduction model has also been proposed. Activated carbons have relatively large particle sizes due to their abundant mesoporous structures, which leads to high performance but low cross-connection between activated carbon particles. Thus, they need to be interconnected via carbon black, which acts as a cross-linking conductor. This paper showed that high energy harvesting efficiency of water diffusion energy harvesters can be achieved through the use of biomass-derived carbon materials. We hope that this study will contribute to the development of water diffusion energy harvesters into practical applications as sustainable solutions to future energy crises.

Sansevieria trifasciata biomass-derived activated carbon by supercritical-CO2 route: Electrochemical detection towards carcinogenic organic pollutant and energy storage application

Activated carbon (AC) has been widely used for electrochemical applications, such as electrochemical sensors, energy storage applications, etc., due to its fine porous structure, volumetric capacitance, and chemical stability. Supercritical-CO2 (SC-CO2) has a fascinating advantage in material science due to its microbubble cavitation, high diffusivity, and high permeability. In the shed of light, we developed a high porous Sansevieria trifasciata biomass-derived AC by SC-CO2 (SC-ST-AC). For comparison purposes, the AC was also prepared in a conventional approach (C-ST-AC). The prepared ACs were characterized through various spectroscopic and microscopic techniques to study their surface morphological character, structural analysis, and phase purity. The electrochemical performance was evaluated by two different applications: electrochemical detection and energy storage application. Based on the results, the SC-ST-AC exhibits higher porous architecture in their morphology and high phase purity with amorphous nature than C-ST-AC. In the preliminary electrochemical analysis, SC-ST-AC achieved higher performance than C-ST-AC. Thus, SC-ST-AC is applied to the real-time application and it exposed a superior limit of detection (0.005 μM L−1) and sensitivity (0.854 μA μM−1 cm−2) towards MA sensing and higher specific capacitance (342.5 F/g for 2 A/g) with 92.09 % of retention at high current density. Thereby, we suggest the SC-CO2 method is a promising approach to develop a highly porous carbon material with excellent electrochemical performance.

(General Student Poster Session Award Winner - 1st Place) Effect of Surface Chemistry and Morphology on Polyluminol-Carbon Redox Active Composites

The rising demand for clean energy and environmental sustainability has led to the growing interest in redox-active organic-carbon composite electrodes for high power and long-lasting energy storage, especially for electrochemical capacitors (EC)[1]. Nitrogen containing organic redox active materials such as the conducting polymer polyluminol chemically polymerized (CpLum) on multiwalled carbon nanotubes (CNT) showed increased capacitive charge storage properties in the composite (CpLum-CNT)[2]. With merely a few nm CpLum, the composite electrodes exhibited reversible faradaic redox reactions and stored c.a. 3x higher volumetric charge than that of bare CNT. Predictions using DFT showed π interactions between the polymers and the CNT substrate. These interactions are thought to have stabilized the composite and contributed to the strong electrochemical performance. In addition to CNT substrates, activated carbons (ACs) offer high specific surface areas, diverse pore size distributions and native surface functionalities owing to their sources. Biomass-derived ACs can serve as low cost, sustainable alternative substrates from feedstocks as pinecone and waste tea [3]–[6].In this work, we investigate the effects of different surface chemistry, porosity and graphitization on CNT and porous activated carbon surfaces towards the redox activity of the CpLum-carbon composite. The surface functionalities of interest include hydroxyl and carboxyl groups owing to their known contributions toward surface wettability and pseudocapacitance while being present on naturally derived ACs. Varying porosity and graphitization also offer insight into the effects of differing specific surface areas, pore sizes, wettability, and conductivity on the CpLum-carbon composites. Figure 1 a. shows a schematic of the groups of interest and graphitization to investigate the surface interaction of luminol on CNT and Figure 1 b. shows the redox active behavior of CpLum-CNT. The insights from these studies will be used to engineer the surface of carbons such as CNTs and ACs to improve the interfacial properties for redox active materials.

Fabrication of biomass derived moisture diffusion energy harvester and statistical analysis of governing factors affecting its performance

In this study, corn stover was carbonized and subjected to a two-step treatment (milling & surface modification) for the preparation of biomass derived activated carbon (Bio-AC). These Bio-ACs were then successfully incorporated for the fabrication of biomass-derived moisture diffusion energy harvester (Bio-MDEH). Characteristics of Bio-ACs such as Fourier transform infrared (FTIR), elemental analysis and zeta potential proved that both the milling & surface modification by acid treatment significantly enhanced the hydrophilicity and conductivity of the Bio-ACs. These Bio-ACs were then coated onto a fibrous material to finally fabricate the Bio-MDEH. The performance of this Bio-MDEH was evaluated by measuring open-circuit voltage (mV), short-circuit current (μA) and the maximum voltage obtained from this device was 826.6 mV. Additionally, touch sensor, soil moisture sensor and light sensor powered by Bio-MDEH showed the signal changes of 1.6 V, 0.85 mV and 50 mV, respectively. Finally, the governing factors affecting the Bio-MDEH’s performance were identified by performing t-test and analysis of variance (ANOVA). The correlated parameters with device’s performance were oxygen/carbon (O/C) ratio, external surface area in a moderate correlation and mesoporous surface areas, conductivity in a strong correlation. This adapted approach seems to be an acceptable option for bio renewable energy harvesting devices.

Nanostructurally engineered TiO2 embedded Mentha aquatica biowaste derived carbon for supercapacitor applications

The invention of cost-effective, clean, and eco-friendly energy storage technology has been capturing a lot of worldwide interest. Herein, biogenically synthesized TiO2 nanoparticles (NPs) were ultrasonically coupled with biomass-derived activated carbon (BAC) to obtain composite (denoted as TiO2@BAC). With the inspiration of nature, Mentha Aquatica leaves extract was employed for biogenic preparation of TiO2 NPs, and residual solid waste (SW) after extract was subsequently utilized for BAC. It is noteworthy that, this unique intensive method does not require any harmful or toxic chemicals and solvents, and no secondary waste is generated. TEM analysis of TiO2@BAC revealed spherical morphology of TiO2 NPs (average size ∼ 18 nm) that were accumulated on nanosheets. Raman, XRD, and XPS manifested the successful construction of TiO2@BAC. The electrochemical performance of the as-synthesized BAC, TiO2 NPs, and TiO2@BAC electrodes was tested towards supercapacitor applications. Notably, the TiO2@BAC electrode exhibited capacitance of 149 F/g at a current density of 1 A/g, which is approximately twice than that of the bare TiO2 electrode (76 F/g) along with excellent capacitance restoration of ∼99%. The TiO2@BAC electrode further revealed outstanding cyclic stability, exhibiting capacitance retention of ∼90% (at 5 A/g) after 10,000 charge/discharge cycles. Furthermore, the TiO2@BAC electrode delivered optimal specific energy density (6.96 Wh/kg) and large power density (2.07 kW/kg at 10 A/g). Moreover, the TiO2@BAC delivers an excellent restoration and retention performances of ∼100 and ∼95% (after 10,000 cycles) at 1 A/g with ∼98% coulombic efficiency in symmetric configuration (maximum cell voltage of 1.2 V).

Thermophysical Characteristics of Novel Biomass-Derived Activated Carbon as a Function of Synthesis Parameters

Activated carbon signifies extensive carbonized materials of a high degree of porosity and has a wide range of applications. The porous and thermal properties of activated carbon (AC) are primarily dependent on the chosen raw material and synthesis conditions. In this article, the thermophysical properties of twelve waste biomass-derived AC samples are investigated and correlated. These AC samples are synthesized from mangrove and waste palm trunk. The samples are different in terms of carbonization temperature (500 and 600°C), activation temperature (600 to 900°C), and the mixing ratio (4 or 6) of the activation chemical, which is potassium hydroxide. The specific heat capacity of W-AC-C600-A900-K6 is found to have the lowest (0.843 to 1.14 kJ kg−1 K−1), and M-AC-C500-A900-K4 shows the highest (1.18 to 1.86 kJ kg−1 K−1) among the studied samples. Experimental data are fitted with the Green-Perry model with an error of less than 2%. This study also accounts for the comparison of specific heat capacity of studied samples and other adsorbents such as AC obtained from different precursors, silica gels, carbon-based consolidated composites, and metal-organic frameworks found in the literature. Moreover, this study gives the insight to synthesize high-quality AC from unknown biomass sources for a particular application.

Facile synthesis of a copper oxide/molybdenum disulfide heterostructure for asymmetric supercapacitors of high specific energy

A unique p-n heterostructural CuO/MoS2 composite is synthesized by a facile hydrothermal method. The active edge-sites of two-dimensional MoS2 nanosheets provide ample surface area for firm attachment of urchin-shaped CuO particles without agglomeration during formation of the p-n heterostructure. The composition and morphology of the heterostructure are characterized by field-emission scanning electron microscopy, X-ray diffraction, Fourier - transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The synergism between CuO and MoS2 enhances electrochemical performance by increasing the number of sites available for redox reactions. Electrochemical measurements establish a specific capacitance of 268 F/g and a cyclic stability of 90.02 % in an alkaline electrolyte solution. An asymmetric supercapacitor fabricated with a CuO/MoS2 positive electrode and a biomass-derived activated carbon (BAC) negative electrode (CuO/MoS2//BAC) achieved a specific energy of 26.66 W h/kg at a specific power of 1599.6 W/kg.

Excellent photocatalytic performances of Co3O4–AC nanocomposites for H2 production via wastewater splitting

Natural sunlight-driven photocatalytic hydrogen production from wastewater is one of the most desirable techniques that can realize future green energy technology. Herein, we report the synthesis and the characterization of the biomass activated carbon (AC)-decorated cobalt oxide (Co3O4) nanocomposites for solar-stimulated photocatalytic hydrogen production from sulphide wastewater. The Co3O4-AC nanocomposites were ultrasonically synthesized by using hydrothermally-grown spinel Co3O4 nanoflakes and biomass-derived AC nanoflakes. Co3O4-AC showed a nanobundle-like aggregated morphology, and exhibited a large specific surface area (~133 m2/g). Through utilizing Co3O4-AC as a photocatalyst for photocatalytic splitting of sulphide wastewater (0.2 M) under solar irradiance with 730 W/m2, an enhanced H2 production efficiency (~70 mL/h) was achieved owing to the synergic effects from 2-dimentionally configured Co3O4 and AC microstructures; i.e., large surface area of Co3O4 and high electrical conductivity of AC. These findings suggest the nanocomposites of Co3O4-AC to hold great promise for the green approach of photocatalytic wastewater splitting.

The adsorption properties of microporous activated carbon prepared from pistachio nut shell for low-concentration VOCs under low-medium temperatures.

The control of low-concentration VOCs in coal-fired flue gas is one of the research hotspots at present. In this work, K2CO3 and K2CO3-KCl were employed to activate the agricultural wastes (pistachio nut shell) to prepare activated carbon (AC), named PSAC-1 and PSAC-2, respectively. By testing the adsorption performance of the prepared AC and commercial activated carbon (CAC) for the five target VOCs, it was observed that the adsorption capacity of PSAC-2 was the best compared to the other two. Particularly, the adsorption capacity of PSAC-2 (225 mg·g-1) for phenol was 3.8 times that of CAC (59 mg·g-1). In addition, the pseudo-first-order model, pseudo-second-order model, and Elovich model all fitted the adsorption process well, which indicated that both physical adsorption and chemical adsorption existed simultaneously, in which physical adsorption played a dominant role and chemical adsorption played a minor role. Weber-Morris kinetic model was used to illustrate the rate-controlling mechanism; the results confirmed that the stage of external membrane mass transfer was the control stage of adsorption rate. The results of this study can provide some references for the commercial production of biomass-derived AC and the removal of VOCs in coal-fired flue gas.