Dual-functional Materials Research Articles

Very low Ru loadings boosting performance of Ni-based dual-function materials during the integrated CO2 capture and methanation process

Herein, the effect of the Ru:Ni bimetallic composition in dual-function materials (DFMs) for the integrated CO2 capture and methanation process (ICCU-Methanation) is systematically evaluated and combined with a thorough material characterization, as well as a mechanistic (in-situ diffuse reflectance infrared fourier-transform spectroscopy (in-situ DRIFTS)) and computational (computational fluid dynamics (CFD) modelling) investigation, in order to improve the performance of Ni-based DFMs. The bimetallic DFMs are comprised of a main Ni active metallic phase (20 wt%) and are modified with low Ru loadings in the 0.1–1 wt% range (to keep the material cost low), supported on Na2O/Al2O3. It is shown that the addition of even a very low Ru loading (0.1–0.2 wt%) can drastically improve the material reducibility, exposing a significantly higher amount of surface-active metallic sites, with Ru being highly dispersed over the support and the Ni phase, while also forming some small Ru particles. This manifests in a significant enhancement in the CH4 yield and the CH4 production kinetics during ICCU–Methanation (which mainly proceeds via formate intermediates), with 0.2 wt% Ru addition leading to the best results. This bimetallic DFM also shows high stability and a relatively good performance under an oxidizing CO2 capture atmosphere. The formation rate of CH4 during hydrogenation is then further validated via CFD modelling and the developed model is subsequently applied in the prediction of the effect of other parameters, including the H2 inlet concentration, inlet flow rate, dual-function material weight, and reactor internal diameter.

Efficient integration of calcium looping with methane Bi-reforming using Pd-enhanced Ni-CaO dual functional nanomaterials

Integration technology of methane bi-reforming (BRM; a combination of methane steam and dry reforming) with calcium looping (CaL-BRM) offered a novel solution to reduce CO2 emission, enabling direct capture and conversion of low-concentration CO2 from sources into value-added products (H2, syngas) within the same reactor. In this study, Ni-CaO-based dual-functional material (DFM), with a small quantity of palladium in the nanostructure, was developed via a continuous two-stage aerosol process and employed in the CaL-BRM. Experimental results demonstrate that Pd-Ni-CaO exhibited high activity and cyclic stability over multiple cycles, maintaining effective CO2 capture (12.0 mmolCO2/gCaO) and BRM performance (>98 % CO2 conversion; H2/CO = 2) at a relatively low temperature (600 °C). Density functional theory calculations reveal that the presence of Pd lowered the activation energy of CH* dissociation, the rate-determining step, from 1.14 to 0.67 eV. The higher adsorption energy (−0.87 eV) of H2O on the Ni-Pd surface and the lower energy barrier (0.62 eV) for subsequent dissociation contributed to the promising catalytic performance in the presence of steam. These findings underscore the significance of utilizing appropriate DFM and demonstrate the potential of CaL-BRM for efficient integrated carbon capture and utilization.

Pivotal copper bimetallic oxide in hierarchical Calcium magnesium materials for low-temperature carbon capture and utilization

Carbon removal from anthropogenic greenhouse gas emissions is essential to achieve net-zero emissions and mitigate climate change, and integrated carbon capture and utilisation (ICCU) has been studied for subsequent in-situ chemical production. However, high temperature and CaO sintering remain critical issues, highlighting the need for improved, low-cost CO2 adsorbents that can be regenerated at lower temperatures. Herin, we innovatively introduce the low-temperature ICCU coupled with reverse water gas shift reactions (RWGS) using dual functional materials (DFMs), exemplifying a range of potential transition metals doped over CaO with or without the MgO support. Among all the prepared DFMs, D-Cu showed desirable enhanced catalytic activity at a comparatively low-temperature performance (550°C) and still maintained a stable CO2 capture capacity (7.0mmol g−1) and CO yield (8.0mmol g−1) with an exceptional CO2 conversion (94.4 %) and CO selectivity (97.6 %) after cyclic hydrogenation. The mechanism study revealed that Ca2CuO3 bimetalliccatalyst in the hierarchical porous 2CaO/MgO matrix of D-Cu plays a crucial role in retaining its cyclic stability, surpassing that of noble D-Pt. Given the ICCU-RWGS performance and cyclic stability of cost-effective D-Cu at reduced operating temperatures, the findings would minimise energy and cost consumption.

N, P co-doped cellulose-based carbon aerogel: A dual-functional porous material for CO2 capture and supercapacitor

N, P co-doped cellulose-based carbon aerogel: A dual-functional porous material for CO2 capture and supercapacitor

Environmental tradeoff on integrated carbon capture and in-situ methanation technology

Compared to conventional CO2 removal methods, carbon capture and in-situ conversion using dual function materials avoid compression and transportation of CO2, which is regarded as a promising technology. Although it brings additional economic benefits, the environmental impacts of CO2 capture and conversion remain unclear. A life cycle assessment of an integrated CO2 capture and methanation system using dual function materials is conducted to investigate its feasibility to reduce global warming. Life cycle inventory is obtained through construction, operation, and disposal process of the integrated system. A dynamic model of CO2 capture and methanation is developed to obtain the operating parameters. Results show that the optimal global warming potential is 0.706 kg CO2,eq per kilogram captured CO2, which indicates the advantages of using dual function materials for carbon mitigation. Global warming potential is a minor factor among the overall normalized environmental impacts, only accounting for 0.5 % of the total normalized impact, while the main factor marine aquatic ecotoxicity accounts for around 73 %, and fresh water aquatic ecotoxicity accounts for around 23 %. Global warming potential is the most affected by green hydrogen input, followed by dual function material input. Results reveal that the integrated CO2 capture and conversion using dual function materials is conducive to carbon mitigation but has significant other environmental impacts, such as marine aquatic ecotoxicity, and the main contributors to the environmental impacts are wind electricity, green hydrogen, refrigerator, and dual function material.

α-Bi2Mo3O12: A Dual-Functional Material for Electrocatalytic Water Splitting and Supercapacitor Applications.

This study explores the functionality of α-Bi2Mo3O12 (BMO) as an electrocatalyst for water splitting and its suitability for supercapacitor applications. BMO was synthesized by the solvothermal method and characterized in pre-calcination [BMO (BC)], post-calcination [BMO (AC)], and base-etched forms [BMO (BE)]. Structural analysis confirmed the formation of α-Bi2Mo3O12 with well-defined crystallographic planes. Electrochemical analysis revealed that BMO (AC) exhibited the lowest overpotential for hydrogen evolution reactions (HER) and BMO (BC) exhibited the lowest overpotential for oxygen evolution reactions (OER), indicating its superior electrocatalytic activity. The Tafel slope and electrochemical impedance spectroscopy results confirmed the superior kinetics and charge transfer properties of BMO material. Furthermore, BMO samples demonstrated excellent stability during prolonged chronoamperometry (CA) testing for 12 h. For supercapacitor performances, the BMO (BE) exhibits a superior specific capacitance value of 398 F/g at 2.0 A/g. Thus, the BMO material delivers prominent electrocatalytic activity as well as supercapacitor performance. Overall, this study demonstrates the potentiality of α-Bi2Mo3O12 in different forms as a dual-functional material for efficient energy storage and conversion.

A multifunctional platform based on ZIF-67 templated NiCo-LDH and Fe3O4 hollow spheres for photocatalytic CO2 conversion and supercapacitors

This work presented a series of hybrid materials F@P-LDHs exhibiting the core-shell structure with PPy as the interface modifier, explored as dual-functional materials for studying photocatalytic reduction of CO2 and electrochemical behaviors. F@P-LDHs served as photocatalysts, effectively convert CO2 into CO without using any sacrificial agents and photosensitizers via the gas-solid mode under the visible light irradiation. The generation rate of CO was as high as 10.32 μmol g−1h−1, which was 5.4 and 6.4 times higher than the original Fe3O4@PPy and NiCo-LDH. The well performance might be ascribed to the generation of type Z heterojunction with the interface modifier PPy, jointly accelerating the separation and migration of photo-generated charge carriers between Fe3O4@PPy and NiCo-LDH. Besides, F@P-LDHs were also developed as supercapacitors, and their electrochemical behaviors were investigated. Their good electrochemical performances were attributed to the synergistic effect among hollow Fe3O4 microspheres, polypyrrole and NiCo-LDH. Therefore, as dual-functional materials, the hybrid materials have great potential in the field of CO2 conversion and supercapacitors.

Mn-enhanced performance of the Ni-CaO/γ-Al2O3 dual function material for CO2 capture and in situ methanation

The CH4 yield over dual functional materials (DFMs) remains low and requires further improvement. In this work, we first examined the influence of Mn on the performance of the Ni-CaO/γ-Al2O3 DFM for CO2 capture and in situ methanation. Our results showed that the MnNi-DFM-3 (MnNi-CaO/γ-Al2O3 DFM) exhibited the best performance at 350 °C, with a CH4 yield of 0.56 mmol/g which is 4 times higher than that of the Ni-DFM-1 (Ni-CaO/γ-Al2O3 DFM) (0.14 mmol/g). Nanoscale characterization revealed that highly scattered Mn3O4 acted as a barrier preventing the agglomeration of Ni-based catalysts. Furthermore, our density functional theory (DFT) analysis demonstrated that the introduction of Mn enhanced the activation of CO2, promoted the dissociation of H2 and intermediates, and reduced the activation energy needed to produce carboxylic acid intermediates on the Ni catalyst. The prepared MnNi-DFM is promising to be a cheap efficient material for CO2 capture and in situ methanation. This work opens up a new pathway for enhancing the performance of DFMs using inexpensive transition metals.

Promoting proximity to enhance Fe-Ca interaction for efficient integrated CO2 capture and hydrogenation

Integrated CO2 capture and utilization (ICCU) using “capture-conversion” dual functional materials (DFMs) paves a cost-effective path for restricting CO2 emissions by eliminating the energy-intensive intermediate processes. The interactions between catalysts and absorbents are believed pivotal in ICCU; however, there is a lack of environment-friendly strategy to fabricate the interaction for industrial applications. Here, we propose a solvent-free mechanochemical approach to promote the interaction by improving the proximity between natural calcium and iron sources. The interaction was systemically investigated and confirmed using XRD, XPS, TEM, TPR, etc. As a result, the mechanochemical approach derived DFM achieved 5.5 mmol/g CO2 capacity, 87 % CO2 conversion, and 100 % CO selectivity at 650 °C, significantly outperforming the CaO-alone benchmark (CO2 capacity < 4.5mmol/g, CO2 conversion < 73 %). Further incorporating MgO would alleviate the sintering and promote the CO2 capture stability (< 15 % decrease after 20 cycles) by acting as a thermal-stable barrier. Based on in situ XRD, it is further confirmed that Fe-Ca interaction exhibits a dynamic looping mechanism in ICCU. The techno-economic analysis strongly supports the superiority of ICCU catalyzed by naturally sourced DFMs on eliminating the energy and H2 consumption for CO2 capture and upgradation. As a result, producing CO via ICCU using mechanochemical derived DFMs exhibits 20 % and 10 % cost decrease compared to the conventional CCU and ICCU using CaO alone scenarios, pointing out the potential of ICCU technology in industrial applications.

An MINLP-based decision-making tool to help microbreweries improve energy efficiency and reduce carbon footprint through retrofits

Microbreweries have greater production costs per litre of beer compared to large breweries, as well as higher carbon footprints. Due to the range of different retrofit technologies available and the different capacities and configurations of microbreweries, it is not always clear what retrofits will improve operations. Therefore, this work proposes a novel mixed-integer nonlinear programming decision-making tool to be used by any microbrewery, that determines the technoeconomic feasibility and sizing of energy efficiency-improving retrofits, including solar and wind power, battery storage, anaerobic digestion, boiler type selection, heat integration by heat storage, and carbon capture via dual-function materials. The model was demonstrated on a real UK microbrewery case study. The model gave an optimal configuration of a 10 m3 anaerobic digester, 30 solar panels outputting 380 W each, an 800 W wind turbine and a 2.3 m3 heat storage tank, reducing annual operating costs by 62.9 % and carbon dioxide emissions by 77.1 % with a payback period of 8 years. The tool is designed to be flexible for use by any microbrewery in any location with any brewing recipe and allow the owner(s) to develop more profitable and sustainable microbreweries.Tweetable abstractMicrobreweries can implement mathematically optimised renewable energy, heat integration and anaerobic digestion to reduce operating costs by 62.9 % and carbon emissions by 77.1 %.

Efficient sorbent/catalyst composites for CO2-mediated oxidative dehydrogenation of ethane via isothermal integrated CO2 capture and utilization

The isothermal integrated CO2 capture and utilization to produce ethylene (ICCU-ODHE) performances of dual functional materials (DFM) were improved by doping five transition metal elements (Fe, Co, Ni, Cu, Zn). The results show that the DFM doped with Zn exhibits excellent ICCU-ODHE performance with an ethylene yield of 35.1 %. The results based on in-situ XPS and DFT calculation show that the doping transition metal elements can reduce the energy barriers for activating ethane and CO2. It is mainly because doping transition metal elements with strong electronegativity can increase the coordinative unsaturated Cr3+ ions to adsorb more ethane molecules, meanwhile, the doping also reduces the charge density of Cr3+ and generates additional unfilled electron orbitals facilitating charge transfer to improve the CO2 and ethane activation. However, the decrease in charge density can increase the difficulty of ethylene desorption and reduce the ethylene selectivity. In addition, the cyclic regeneration experiment shows that the ICCU-ODHE performance of DFM can decrease with the increase of cycles, however, significant performance restoration is achievable after regeneration in the air at 650 °C, attributed to the limited graphitization of coke deposition on the DFM.

Taking dual function materials (DFM) from the laboratory to industrial applications: A review of DFM operation under realistic integrated CO2 capture and utilization conditions

Taking dual function materials (DFM) from the laboratory to industrial applications: A review of DFM operation under realistic integrated CO2 capture and utilization conditions

Post-crosslinking knitting strategy for triazine-functionalized ionic hypercrosslinked polymers: Enhanced CO2 adsorption and conversion

Pore engineering has gained significant recognition as a pivotal strategy to tailor the structure and functionality of porous materials. In this study, a post-crosslinking knitting strategy was employed to fabricate a series of triazine-functionalized ionic hypercrosslinked polymers (IHCPs) using low specific surface area ionic polymers as precursors and external crosslinkers α,α′-dichloro-p-xylene (DCX) and α,α′-dibromo-p-xylene (DBX) through the Friedel Crafts alkylation reaction. This post-crosslinking knitting methodology increases the specific surface area of the resulting IHCPs, leading to enhanced CO2 adsorption capabilities (reaching 1.92 mmol·g−1 at 1 bar and 273 K), enhanced a remarkable 5.6-fold increase in CO2 uptake compared to the original ionic polymers. Of particular interest, inclusion of –NH– groups in PTA-2-DBX exhibits a synergistic catalytic effect facilitated by hydrogen bonding interactions that enable efficient conversion of CO2 into various cyclic carbonates under solvent- and cocatalyst-free conditions with yields exceeding 99 %. Furthermore, PTA-2-DBX demonstrates excellent recyclability while maintaining its activity even after five consecutive cycles. This study offers an effective approach for modulating pores in ionic polymers while highlighting the promising applications of triazine-functionalized IHCPs as dual-functional materials for both CO2 capture and conversion.

Ammonia controlled synthesis of NiO nanosheet arrays for high-performance electrochromic-supercapacitors

To optimize the synthesis process and improve the electrochromic and energy storage performance of NiO, in this paper, an ammonia hydrothermal method is used to prepare NiO nanosheet array electrodes with dual-functions of electrochromic and energy storage. When the concentration of ammonia reaches pH = 11.5, the prepared electrode exhibits optimal optical modulation capability (79.2 % at 620 nm). Additionally, this electrode also provides a large area specific capacitance (69.5 mF/cm² at 0.2 mA/cm²), good rate capability (maintaining 46.7 mF/cm² at 1.0 mA/cm²), and excellent capacitive stability (retaining 96 % of the initial capacitance after 5000 cycles). These excellent performances are mainly attributed to the hierarchical assembled nanosheets structure, which has a large active surface area and short ion transport paths. Furthermore, the uniform and interlinked self-assembled structure, as well as the preset seed layer significantly enhance the film's structural stability and the adhesion to the substrate. Notably, we also construct electrochromic-supercapacitors (ECSCs). During the charging process, two series-connected ECSCs turn dark brown and light up an LED lamp, while during the discharging process, the ECSCs gradually becomes colorless, and the LED lamp goes out. This study provides directions for the preparation of novel dual-functional visual energy storage materials and boosts the development of dual-functional electrochromic-energy storage devices.

Engineering nanoparticle structure at synergistic Ru-Na interface for integrated CO2 capture and hydrogenation

The development of dual functional material for cyclic CO2 capture and hydrogenation is of great significance for converting diluted CO2 into valuable fuels, but suffers from kinetic limitation and deactivation of adsorbent and catalyst. Herein, we engineered a series of RuNa/γ-Al2O3 materials, varying the size of ruthenium from single atoms to clusters/nanoparticles. The coordination environment and structure sensitivity of ruthenium were quantitatively investigated at atomic scale. Our findings reveal that the reduced Ru nanoparticles, approximately 7.1 nm in diameter with a Ru-Ru coordination number of 5.9, exhibit high methane formation activity and selectivity at 340 °C. The Ru-Na interfacial sites facilitate CO2 migration through a deoxygenation pathway, involving carbonate dissociation, carbonyl formation, and hydrogenation. In-situ experiments and theoretical calculations show that stable carbonyl intermediates on metallic Ru nanoparticles facilitate heterolytic C–O scission and C–H bonding, significantly lowering the energy barrier for activating stored CO2.

Li/Na/K carbonate solar salts for enhanced and integrated carbon capture and utilization via reverse water gas shift (ICCU-RWGS)

This study introduces a novel ICCU-RWGS process using Li, Na, and K carbonates mixed with boric acid as dual functional materials, enhancing CO2 capture and conversion without traditional CaO adsorbents. These molten salts, compatible with solar energy systems, enable efficient integration with CSP, storing heat from CO2 capture for utilization. The addition of boric acid significantly boosts CO2 uptake and conversion, achieving 2.0 mmol, 1.1 mmol, and 1.3 mmol CO2 uptake with conversion of 51.1 %, 58.3 %, and 57.6 % over three cycles, respectively. A 10-cycle test confirmed stable performance, with conversion rates between 53.0 % and 58.7 %. Characterization techniques (XRD, SEM, TEM, XPS, in-situ DRIFTS) revealed new borate phases after CO2 capture. TG-DSC analysis showed exothermic peaks during CO2 capture and RWGS stages, indicating that molten salt has the potential to generate heat for CSP systems, thus offering efficient CO2 conversion and sustainable energy recovery.

Quantum-Sized Co Nanoparticles with Rich Vacancies Enabled the Uniform Deposition of Lithium Metal and Fast Polysulfide Conversion.

The notorious polysulfide shuttling and uncontrollable Li-dendrite growth are the main obstacles to the marketization of Li-S batteries. Herein, a dual-functional material consisting of vacancy-rich quantum-sized Co nanodots anchored on a mesoporous carbon layer (v-Co/meso-C) is proposed. This material exposes more active sites to improve its reaction performance and simultaneously realizes excellent lithiophilicity and sulfiphilicity characteristics in Li-S electrochemistry. As Li metal deposition hosts, v-Co/meso-C shows small nucleation overpotential, low polarization, and ultra-long cycling stability in both half and symmetric cells, as confirmed by experimental studies. On the S cathode side, experimental and theoretical calculations demonstrate that v-Co/meso-C enhances the adsorption of polysulfides and boosts their catalytic conversion rate. This, in turn, suppresses the shuttle effect of polysulfides and improves sulfur utilization efficiency. Finally, a shuttle-free and dendrite-free v-Co/meso-C@Li//v-Co/meso-C@S full cell is fabricated, exhibiting excellent rate performance (739 mAhg-1 at 5.0 C) and good cyclability (capacity decay rate is 0.033% and 0.035% per cycle at 2.0 and 5.0 C, respectively). Even a pouch cell with high sulfur loading (5.5mgcm-2) and lean electrolyte/sulfur (4.8µLmg-1) can still work 50 cycles with 80% capacity retention rate. This study shows far-reaching implications in the design of dendrite-free, shuttle-free Li-S batteries.

Rare earth oxide promoted Ru/Al2O3 dual function materials for CO2 capture and methanation: An operando DRIFTS and TGA study

Dual-function materials (DFMs) combine sorbent and catalytic components to perform selective CO2 capture and subsequent hydrogenation. This study explores the performance of rare-earth oxides (REOs) as CO2 adsorption sites on Ru/Al2O3. REOs increase CO2 uptake by upwards of +60 % by enhancing the overall catalyst surface basicity and favoring metal–support interactions. Thermogravimetric analysis during CO2 adsorption-hydrogenation cycles exhibited significant catalytic activity and enhanced stability of Ru-REO/Al2O3 at temperatures as low as 200 °C. This leads to methane production of 50–85 µmol g−1, surpassing recently reported values obtained for alkali and alkali-earth promoted Ru-based materials operated at 250 °C. The highest performing studied DFM, RuNd2O3/Al2O3, achieved 85 % CO2 capture efficiency and steadily produced methane in cyclic operation (+120 % CO2 uptake relative to Ru/Al2O3). Operando DRIFTS revealed that the dominant mechanism for methane formation is the hydrogenation of ruthenium carbonyls, which are stabilized by REOs. Upon CO2 exposure, surface carbonates and bicarbonate species form more abundantly on DFMs than on Ru/Al2O3. This confirms that REOs enhance the adsorption and retention of carbonates, which generate additional promoter-related reaction pathways during low-temperature hydrogenation. These findings are crucial in the advancement of sustainable, wider operation range carbon capture and utilization technologies.

Fabrication of dual-functional smart materials: 2D-WO3/rGO nanocomposite for electrochemical detection and photocatalytic degradation of tetracycline

The extensive utilization of the antibacterial agent tetracycline (TC) in pharmaceuticals and livestock farming has sparked considerable health apprehensions for the welfare of both animals and humans. The presence of TC drug residues in soil, rivers, lakes, and groundwater further exacerbates these concerns. To address these issues, we synthesized WO3/rGO nanocomposites using a simple hydrothermal method and explored their bifunctional catalyst properties for the first time. These nanocomposites were investigated for their potential applications in electrochemical sensing and photocatalytic degradation of TC drug. The electrocatalytic oxidation of TC drug using the WO3/rGO/Glassy Carbon Electrode (GCE) nanocomposites demonstrated good sensitivity, low detection limit, low quantification limit and wide linear range of 1.708 µA µM−1 cm−2, 202 nM, 0.202 µM and 0.1–400 µM, respectively. Moreover, we assessed the WO3/rGO/GCE nanocomposites effectiveness in detecting TC drug in real samples, including milk, lake water, fish, and tap water, and found the recovery results to be satisfactory. Additionally, the nanocomposites displayed noteworthy photocatalytic activity in degrading the TC drug. The as-prepared WO3/rGO nanocomposites exhibited an impressive degradation efficiency of 87.5 % over 120 minutes under UV–visible light irradiation. Radical trapping tests confirmed that the *OH- radicals played a significant role in the degradation process. Our study highlights the outstanding electrochemical and photocatalytic properties of WO3/rGO nanocomposites, positioning them as highly promising materials for future biomedical and environmental applications.

Cu promoted Ni-Ca dual functional materials for integrated CO2 capture and utilization in O2-containing flue gas: Eliminating the delay in the utilization stage

Integrating CO2 capture and utilization by dry reforming methane (ICCU-DRM) technology is promising in concentrating and utilizing diluted CO2 from flue gas, which depends on developing Dual Functional Materials (DFMs) with adsorption and catalytic sites. Ni-Ca materials are widely applied in ICCU-DRM due to their excellent catalytic and CO2 adsorption properties. Nevertheless, the challenge remains that oxygen in the actual flue gas would oxidize the active Ni, leading to a delay in the DRM stage. In this work, Cu-promoted, ZrO2-stabilized Ni-Ca based DFMs were developed, which suppressed the delay and enhanced the performance of the DRM reaction. Attribute to the excellent reducing properties, Cu could be rapidly reduced in the CH4 atmosphere and further promote the reduction of NiO to the catalytically active Ni monomers by activating methane to generate reactive hydrogen (H*). What’s more, attributed to the disappearance of delay times, it is accompanied by a satisfying yield distribution with a 0.11 decrease in H2/CO ratio and an improvement in conversion, especially CH4 conversion with an increase of more than 10%. In addition, the bifunctional material also exhibits favorable cycling stability due to the stabilizers.