Dual-functional Materials Research Articles

Fabrication of Pd/MnFe2O4 bifunctional 2-D nanosheets to enhance the yield of HCOOH from CO2 cathodic reduction paired with anodic oxidation to CH3OH

Highly active and stabilized bifunctional electrocatalysts contributed to the reduction of hazardous atmospheric pollutants through paired electrochemical reactions. Herein, spherical-like Pd nanoparticles were successfully grown on two-dimensional MnFe2O4 nanosheets (2-D Pd/MnFe2O4 NSs) via microwave irradiation and tested in an electrochemical cell as dual-functional hybrid electrode material. Several characterization techniques were used to determine the morphological, structural and chemical properties of the as-prepared bifunctional Pd/MnFe2O4 electrocatalysts. The 2-D Pd/MnFe2O4 NSs exhibited a higher specific surface area of 390 m2 g−1 with a pore volume of 0. 327 cm3 g−1, resulted in a high CO2 reduction activity (CO2 RR) towards the desired production of formic acid. The HCOOH yield was optimized by varying the cell potential, electrolyzer reaction time, and electrolyte concentration. The maximum yield of HCOOH was found to be 476 μmol h−1 cm−2 with a Faradic efficiency of (FE) 96.9%. Furthermore, CO2 RR was coupled with CH3OH oxidation reaction (CH3OH OR) to evaluate the paired electrochemical activity of the bifunctional Pd/MnFe2O4 electrocatalysts. The results showed that Pd/MnFe2O4 had a high production rate of HCOOH of about 625 µmol h−1 cm−2 with FE of 97.5% at −1.0 V vs. RHE in optimized electrolyzer concentrations. During CH3OH OR, many H+ and e− were formed, which is the key to increasing HCOOH yield through the paired electrolyzer. The mechanism of the paired electrochemical reaction was also described in detail. This study showed that integrated future bifunctional fuel cells utilizing CH3OH combined with CO2 reduction strategies, could achieve zero gas exhaust emission and sustainably produce high value-added chemicals.

Closing the Carbon Cycle with Dual Function Materials

Carbon dioxide (CO2) is one of the most harmful greenhouse gases, and it is the main contributor to climate change. Its emissions have been constantly increasing over the years due to anthropogenic activities. Therefore, efforts are being made to mitigate emissions through carbon capture and storage (CCS). An alternative solution is to close the carbon cycle by utilizing the carbon in CO2 as a building block for chemicals synthesis in a CO2 recycling approach that is called carbon capture and utilization (CCU). Dual function materials (DFMs) are combinations of adsorbent and catalyst capable of both capturing CO2 and converting it to fuels and chemicals in the same reactor with the help of a coreactant. This innovative strategy has attracted attention in the past few years given its potential to lead to more efficient synthesis through the direct conversion of adsorbed CO2. DFM applications for both postcombustion CCU and direct air capture (DAC) and utilization have been demonstrated to date. In this review, we present the unique role DFMs can play in a net zero future by first providing backgrounds on the types of CCU methods of varying technological maturity. Then, we present the developed applications of DFMs such as the synthesis of methane and syngas. To better guide future research efforts, we place an emphasis on the connection between DFM physiochemical properties and performance. Lastly, we discuss the challenges and opportunities of DFM development and recommend research directions for taking advantage of their unique role in a low-carbon circular economy.

Dual function materials (Ru+Na2O/Al2O3) for direct air capture of CO2 and in situ catalytic methanation: The impact of realistic ambient conditions

A dual function material (DFM) comprised of 1% Ru, 10% Na2O/γ − Al2O3 was studied for combined direct air capture (DAC) of CO2 and catalytic methanation in a temperature swing operation. In the newly proposed operation, the DFM captures CO2 (400 ppm) from air at ambient conditions. The material is then heated in H2 to a temperature sufficient for catalytic conversion of the captured CO2 to renewable natural gas. In this study, we demonstrate high CO2 adsorption capacity and rates at ambient conditions (25 °C); the adsorbed CO2 is then successfully catalytically methanated upon heating in H2. Adsorption was also carried out in humid conditions, more closely simulating ambient air. Adsorption and methane production were greatly improved with stable initial performance. The rate of adsorption is shown to be flowrate-dependent, which is critical for future reactor design.

Harnessing efficient in-situ H2O2 production via a KPF6/BiOBr photocatalyst for the degradation of polyethylene

• KPF 6 doped BiOBr were successfully synthesized using a simple one-pot hydrothermal method. • The photocatalytic H 2 O 2 production of 20 wt% KPF 6 /BiOBr is 1.96 times higher than pure BiOBr. • Plastic bags were decomposed by KPF 6 /BiOBr in conjunction with the in-situ generation of H 2 O 2 . • Hydroxyl radicals play a key role in the polyethylene degradation. • A potential mechanism for H 2 O 2 production and polyethylene degradation was proposed. The development of cost-effective dual-function photocatalytic materials to advance clean energy generation and storage combined with superior pollutant degradation performance has thus far remained challenging. For this study, potassium hexafluorophosphate (KPF 6 ) was introduced to modify BiOBr via a simple one-pot hydrothermal method, where uniformly dispersed KPF 6 on BiOBr nanosheets improved H 2 O 2 yields and the pollutant degradation performance. Such materials have proven to be critical for low bandgap and enhanced surface charge separation for efficient H 2 O 2 production. The optimized sample of 20 wt% KPF 6 /BiOBr showed a H 2 O 2 production rate of 53.36 mg·L –1 , which was much higher than that of pure BiOBr (27.19 mg·L –1 ). Nitroblue tetrazolium chloride (NBT) superoxide radical detection results suggested that two-step single-electron oxygen reduction was the primary pathway. More importantly, discarded polyethylene bags from supermarkets have been decomposed though the in-situ generation of H 2 O 2 using KPF 6 /BiOBr materials, and the mass loss of plastics was 2.33 times higher than that of the pure BiOBr. This research offers new perspectives toward the development of new functionalized materials for H 2 O 2 production, while improving capacities for the degradation of plastics.

Target-directed design of dual-functional Z-scheme AgIn5S8/SnS2 heterojunction for Pb(II) capture and photocatalytic reduction of Cr(VI): Performance and mechanism insight

• Dual-functional Z-scheme AgIn 5 S 8 /SnS 2 heterojunction was target-directed designed. • AgIn 5 S 8 /SnS 2 has high adsorption capacity for Pb(II) capture. • AgIn 5 S 8 /SnS 2 shows superior photocatalytic activity for Cr(VI) reduction. • Pb(II) adsorption was attributed to S-Pb coordination and electrostatic attraction. • Z-scheme photocatalytic mechanism was based on internal electric field. Target-directed design and synthesis of dual-functional materials with superior adsorption for Pb(II) and photocatalytic activity for Cr(VI) reduction are challenging but of vital importance for heavy metal-laden wastewater remediation. In this work, dual-functional Z-scheme AgIn 5 S 8 /SnS 2 heterojunctions were designed according to hard-soft acid-base theory and band structure matching, and were synthesized by simple hydrothermal reaction. The AgIn 5 S 8 /SnS 2 has high adsorptive capacity for Pb(II) with almost 100% Pb(II) removal, and the adsorptive capacity of AgIn 5 S 8 /SnS 2 for Pb(II) is about 5 and 3.3 times that of AgIn 5 S 8 and SnS 2 , respectively. Moreover, AgIn 5 S 8 /SnS 2 shows outstanding visible-light photocatalytic performance for Cr(VI) reduction with 96% reduction efficiency. The XPS analysis, Zeta potential, DFT calculation reveal that S atoms are dominant adsorption sites, and the adsorption of Pb(II) is more favorable on AgIn 5 S 8 (3 1 1)/SnS 2 (1 0 1) than SnS 2 (1 0 1) or AgIn 5 S 8 (3 1 1) due to the remarkable coordination of S atoms with Pb(II) and strong electrostatic attraction. Furthermore, the photocatalytic mechanism of Z-scheme AgIn 5 S 8 /SnS 2 heterojunction for Cr(VI) reduction was identified and uncovered by experimental studies.

Insights into Nickel-Based Dual Function Materials for CO2 Sorption and Methanation: Effect of Reduction Temperature

Ni-MgO dual function materials (DFMs) show promise for integrated CO2 sorption and methanation. To improve CO2 sorption capacity, Ni-MgO DFMs are promoted with alkali metal nitrates. However, the h...

Metal oxide‐doped Ni/CaO dual‐function materials for integrated CO2 capture and conversion: Performance and mechanism

AbstractIntegrated CO2 capture and conversion (ICCC) into valuable chemicals such as CH4 and CO is a promising approach to mitigate anthropogenic CO2 emissions. In this work, we prepared a series of metal oxide (MxOy, M = Mg, Al, Mn, Y, Zr, La, and Ce)‐doped Ni/CaO dual‐function materials (DFMs) and applied them to the ICCC process. The property–performance relationship of the DFMs was studied, and the conversion mechanism of the captured CO2 was explored. For any DFM at any ICCC cycle (20 cycles in total), the CO2 captured at the carbonation stage was completely released as CH4, CO, and CO2 at the conversion stage. Among all DFMs, Ni/CaZr(O) showed the best ICCC performance because of its good thermal stability. The conversion of captured CO2 on the DFMs proceeded via a two‐step mechanism, where CO2 was first released from CaCO3 and then converted into CH4 at Ni sites and CO at CaO sites.

Screening of Adsorbent/Catalyst Composite Monoliths for Carbon Capture-Utilization and Ethylene Production.

Combining CO2 adsorption and utilization in oxidative dehydrogenation of ethane (ODHE) into a single bed is an exciting way of converting a harmful greenhouse gas into marketable commodity chemicals while reducing energy requirements from two-bed processes. However, novel materials should be developed for this purpose because most adsorbents are incapable of capturing CO2 at the temperatures required for ODHE reactions. Some progress has been made in this area; however, previously reported dual-functional materials (DFMs) have always been powdered-state composites and no efforts have been made toward forming these materials into practical contactors. In this study, we report the first-generation of structured DFM adsorbent/catalyst monoliths for combined CO2 capture and ODHE utilization. Specifically, we formulated M-CaO/ZSM-5 monoliths (M = In, Ce, Cr, or Mo oxides) by 3D-printing inks with CaCO3 (CaO precursor), insoluble metal oxides, and ZSM-5. The physiochemical properties of the monoliths were vigorously characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 physisorption, elemental mapping, pyridine Fourier transform infrared spectroscopy (Py-FTIR), H2-temperature-programmed reduction (H2-TPR), and NH3-temperature-programmed desorption (NH3-TPD). Their performances for combined CO2 adsorption at 600 °C and ODHE reaction at 700 °C under 25 mL/min of 7% C2H6 were then investigated. The combined adsorption/catalysis experiments revealed the best performance in Cr-CaO/ZSM-5, which achieved 56% CO2 conversion, 91.2% C2H4 selectivity, and 33.8% C2H4 yield. This exceptional performance, which was improved from powdered-state DFMs, was attributed to the high acidity and numerous oxidation states of the Cr2O3 dopant which were verified by NH3-TPD and H2-TPR. Overall, this study reports the first-ever proof-of-concept for 3D-printed DFM adsorbent/catalyst materials and furthers the area of CO2 capture and ODHE utilization by providing a simple pathway to structure these composites.

Integrated direct air capture and oxidative dehydrogenation of propane with CO2 at isothermal conditions

Developing routes of utilizing CO2 emissions is important for long-term environmental preservation, as storing such emissions underground will eventually become unsustainable. One way of utilizing CO2 emissions is as a light-oxidant feedstock for oxidative dehydrogenation of propane (ODHP) to propylene. However, the adsorption and reaction steps typically occur at widely different temperatures, meaning that the thermal gradients – and by extension process energy requirements – are often unreasonably high. In recent years, dual-functional materials (DFMs) – i.e., materials comprised of a high temperature adsorbent phase alongside a heterogeneous catalyst – have been employed for combined CO2 adsorption and utilization over one material within a single bed using a reduced thermal gradient. However, these materials have never been formed into practical contactors and have never been applied to ODHP applications. Therefore, in this study we manufactured the first-generation of DFM adsorbent/catalyst monoliths, comprised of CaO (adsorbent) and M@ZSM-5 (M = V-, Ga-, Ti-, or Ni-oxide) heterogeneous catalysts, using our novel direct metal-oxide 3D printing technique. The monoliths were vigorously characterized using N2 physisorption, C3H8-DRIFTS, NH3-TPD, Py-FTIR, H2-TPR, XRD, XPS, and elemental mapping and were assessed for CO2 capture/ODHP utilization at 600–700 ºC. The adsorption/catalysis experiments revealed that these materials can perform both processes effectively at 600 ºC, with reduced propylene yield at higher temperature, which eliminated the need for a thermal gradient between the adsorption and catalysis steps. Between the various samples, the Ti-doped monolith generated the best balance of CO2 conversion (76%) and propylene selectivity (39%), due to the high dispersion of TiO2, favorable redox properties and controlled acidity of the dopant. However, it was also found that varying the metal dopant could be used to control the heuristics of CO2/C3H8 conversion, C3H6 selectivity, and C3H6 yield, meaning that the manufacturing process outlined herein represents a promising way of tuning the chemical properties of structured DFM adsorbent/catalyst materials. More importantly, this study establishes a promising proof-of-concept for 3D printing as a facile means of structuring these exciting composite materials and expands DFMs to the previously unexplored application of ODHP.

Covellite Nanodisks and Digenite Nanorings: Colloidal Synthesis, Phase Transitions, and Optical Properties

Copper sulfide nanoparticles represent a class of dual-functional materials whose optical properties are dominated by interband electronic transitions and intraband plasmon resonances, both of whic...

Iron-doped nanoflakes of layered double hydroxide of nickel for high-performance hybrid zinc batteries

Hybrid Zn–air and Zn–M (M represents transition metal oxide/hydroxide) batteries combined at the cell level take the advantages of Zn–air high-capacity and Zn–M high cell voltage. However, the performance of a Zn–air/M battery relies on finding a dual-functional cathode material, which can effectively serve both battery's chemistries. Here, we demonstrate the superior performance of a hybrid battery cathode based on Fe-doped Ni double hydroxide nanoflakes and activated carbon material. Fe doping transforms the disordered crystal structure of Ni hydroxide to a stable hydrotalcite-type structure with significantly enhanced redox conversion capacity, improved electric conductivity, and superior oxygen evolution reaction activity. Therefore, the hybrid battery exhibits a high total energy density, unprecedented energy conversion efficiency (87% at 4 mA/cm2), and superior power density (100 mW/cm2 at 60 mA/cm2) that outperform reported hybrid batteries of other cathode materials. Moreover, the hybrid Zn–air/Ni1−xFex–layered double hydroxide battery is featured with the capability of high-rate charging owing to the rapid kinetics of the redox reactions and the excellent catalytic activity of the cathode materials.

Dual-functional UiO-type metal-organic frameworks for the sensitive sensing and effective removal of nitrofurans from water

Herein, a dual-functional platform for simultaneous detection and removal of Nitrofurans (NFs), a class of widely used antibiotics, from aqueous solution is developed on the basis of water-stable luminescent UiO-Type Metal-Organic Frameworks (Zr-fcu-sti). Specifically, Zr-fcu-sti responds to NFs at parts per billion (ppb) levels based on the efficient luminescence quenching and is one of the most sensitive luminescent MOF-based sensing materials. The efficient luminescence quenching can be explained by a combined effect of the strong absorption of NFs at the excitation wavelength and the photo-induced electron transfer process from the ligand of Zr-fcu-sti to NFs. In addition, NFs can obviously cause the red shift of the probe's maximum emission, which can be used as an indicator for the qualitative detection of NFs, clearly distinguishing them from other types of antibiotics. Meanwhile, its suitable pore size, large surface areas and the widely distributed hydrogen bonding sites on pore surfaces endow the MOF with excellent uptake capacity toward NFs in aqueous environment. These results show that, as a water-stable dual-functional material with great application prospects, Zr-fcu-sti can achieve high-sensitivity fluorescence sensing and efficient adsorption of NFs from water.

Highly selective CO2 capture and photoreduction over porous carbon nitride foams/LDH monolith

Sunlight-driven photocatalytic CO2 into useful carbon compounds is an ideal way to mitigate the greenhouse effect. However, this strategy is limited by poor light absorption and rapid photoexcited electron-hole recombination of traditional photocatalysts. Here, a g-C3N4 (CN) foam/LDH heterojunction monolith (NCF) was fabricated by growing NiFe-LDH in situ on the porous CN foam substrate. The composite had good air permeability and light transmittance, which improves light-harvesting, CO2 capture, and interfaces charge transfer of the NCF. The results show that the NCF catalyst has good CO2 adsorption performance (1.52 mmol g−1) and enhanced CO2 photoreduction activity (55.1 μmol g-1h−1), which is ∼ 10 times higher than that of pure LDHs powder. Furthermore, the practical applicability of the NCF monolith with different thicknesses is illustrated via the CO2 photoreduction test for the first time. This work could shed light on the development of dual-functional materials for efficient capture and photoreduction of CO2.

Optoelectronic/memory storage properties of triphenylamine-based dual-function electrochromic materials

Two electrochromic polymers containing triphenylamine groups with memory storage function were synthesized. The structures of the polymers have been characterized in detail. The polymers had good solubilities, excellent thermal stabilities and high fluorescence intensities. The reversible redox peak can also be clearly observed in the cyclic voltammogram, and the electrochromic color contrast was obvious. In addition, the polymers can also be used as memory storage materials with excellent "write-read-erase-rewrite" performance. Among them, the P2 film presented noticeable color changed from light yellow to pine green during the voltage 0 V–1.4 V, the coloring time was 3.3 s and the bleaching time was 3.7 s, the coloration efficiency was 207 cm2 C−1. The ON/OFF current ratio of P2 was 103.1 and the threshold voltage of P2 was 0.91 V. The results showed that these polymers have broad application prospects in the field of dual-function materials.

Ni-CaO dual function materials prepared by different synthetic modes for integrated CO2 capture and conversion

Dual-functional materials (DFMs) present broad prospects in CO2 capture and in-situ conversion to value-added products using renewable energy. Herein, we proposed and demonstrated three different synthetic modes for preparing Ni-CaO DFMs using carbide slag as calcium precursor. CO2 sorption and in-situ hydrogenation performance of the Ni-CaO DFMs was evaluated using a fixed-bed reactor. Results indicated that CO2 sorption capacity and CO productivity of the synthesized Ni-CaO DFMs depended on the synthetic modes. The desired Ni/CS-P30-C synthesized by acid pretreatment of carbide slag followed by citric acid complex exhibited a high CO2 sorption capacity (13.28 mmol/g DFMs) and a great CO productivity (5.12 mmol/g DFMs) under the isothermal testing temperature of 650 °C. The sample also showed stable CO2 uptake and CO productivity within 17 cycles. The good CO2 sorption and in-situ hydrogenation performance were associated with the better textural properties, smaller particle size and more uniform dispersion of Ni species, which were resulted from propionic acid pretreatment and citric acid complex processes. In addition, Ni-CaO pellet with high mechanical strength (2.88 MPa) and abrasion ability (weight loss of 2.36% after 3000 rotations). had also been prepared by the extrusion-spheronization method. The pelletization process adversely affected the CO2 sorption and in-situ hydrogenation performance, but the pellet exhibited good stability in cyclic operations.

Deciphering the O-Glycosylation of HKU1 Spike Protein With the Dual-Functional Hydrophilic Interaction Chromatography Materials.

HKU1 is a human beta coronavirus and infects host cells via highly glycosylated spike protein (S). The N-glycosylation of HKU1 S has been reported. However, little is known about its O-glycosylation, which hinders the in-depth understanding of its biological functions. Herein, a comprehensive study of O-glycosylation of HKU1 S was carried out based on dual-functional histidine-bonded silica (HBS) materials. The enrichment method for O-glycopeptides with HBS was developed and validated using standard proteins. The application of the developed method to the HKU1 S1 subunit resulted in 46 novel O-glycosylation sites, among which 55.6% were predicted to be exposed on the outer protein surface. Moreover, the O-linked glycans and their abundance on each HKU1 S1 site were analyzed. The obtained O-glycosylation dataset will provide valuable insights into the structure of HKU1 S.

Dual-Functional Graphene Oxide-Based Photothermal Materials with Aligned Channels and Oleophobicity for Efficient Solar Steam Generation.

Desalination by solar steam generation (SSG) has emerged as one of the most efficient approaches to address the issue of global water shortage. In this work, novel graphene oxide (GO)-based solar steam generators (GO-SSGs) with aligned channels were prepared by directional freezing and simple carbonization of a hydrogel composed of GO and poly(vinyl alcohol) (PVA). Benefitting from their excellent light absorption (light absorption efficiency exceeds 94%), better thermal insulation (thermal conductivity, 0.259 W/(m K)), and suitable porous structure, which facilitates rapid water transportation, the GO-SSGs show superior SSG performance with a high solar energy conversion efficiency of up to 92% achieved under an irradiation of 1.0 kW/m2. Interestingly, uniquely aligned channels endow them with good salt-rejection performance; the solar energy conversion efficiency of GO-SSGs in 20 wt % NaCl, KCl, and MgCl2 brine can reach more than 85%. To improve their antifouling performance, a chemically hydrophilic and oleophobic modification was conducted, making it possible to run SSG even in oily wastewater; for instance, a solar energy conversion efficiency of 84% was obtained in an aqueous solution containing 10 wt % n-hexadecane. Compared with the existing photothermal materials, these materials show advantages of simple manufacture, high SSG efficiency, superior salt tolerance, and antifouling performance, which make them promising candidates as a kind of new high-performance photothermal materials for desalination even in oily wastewater, thus further expanding the scope of their practical SSG application.

A Novel Tea factory waste metal-free catalyst as promising supercapacitor electrode for hydrogen production and energy storage: A dual functional material

In this study, the catalyst produced from tea factory waste (TFW) was used for the first time for hydrogen production by methanolysis of sodium borohydride (NaBH4). The produced material had a dual function as both catalyst and supercapacitor; therefore, it was named ‘cap-cat’(capacitor-catalyst) by us. In this context, TFW was treated with acetic acid for 24 h at 80 °C. The sample was then subjected to combustion in the oven to synthesize the catalyst. Afterward, the most efficient TFW-CH3COOH catalyst was synthesized by evaluating different acid ratios, burning temperatures and times. The best conditions for the acetic acid ratio, burning temperature, and time were found out 3 M, 300 °C, and 60 min. The characterization of the catalyst was done using SEM-EDX, FTIR, XRD analysis. Hydrogen generation experiments from NaBH4 by methanolysis were performed at various catalyst concentrations in the range of 0.05–0.2 g, diverse NaBH4 ratio of 1 to 7.5%, and at different reaction temperatures (30–60 °C). The HGR of the synthesized catalyst was recorded as 3096.4, 8367.5, 11227.9, and 23,507 mLmin-1gcat-1 for these temperatures (30, 40, 50, and 60 °C), respectively. Also the activation energy was calculated as 38.6 kJ mol−1. Subsequently, the CV (cyclic voltammetry) and charge–discharge curves of the prototypes produced were substantially similar to the supercapacitor curves in the literature. Gravimetric capacitance was found to be 155F/g at a current density of 2 A/g.

Investigation of Combined Capture–Destruction of Toluene over Pd/MIL-101 and TiO2/MIL-101 Dual Function Materials

Investigation of Combined Capture–Destruction of Toluene over Pd/MIL-101 and TiO₂/MIL-101 Dual Function Materials

Insights into the cyclic CO2 capture and catalytic methanation over highly performing Li-Ru/Al2O3 dual function materials

The combined CO2 capture and in-situ methanation using renewable hydrogen over dual function sorbent-catalyst materials is a chemical looping process with strong potential to increase the efficiency and reduce the cost of current CCU technologies. In this work, we set out to develop highly performing Lithium-Ruthenium/Al2O3 investigating synergic and mechanistic aspects involved in the alternate CO2 adsorption and hydrogenation phases. Catalysts with low Ru loading (max 1% wt.) and fixed dispersion on Al2O3 spheres were promoted with variable amounts of Li (1–5% wt.) and characterized by BET, PSD, XRD, H2 chemisorption, CO2-TPD, TG-MS, H2-TPSRx and CO2 catalytic methanation under continuous flow conditions. Transient CO2 storage/methanation cycles were studied in a fixed bed reactor that was operated at several temperature levels (250–350 °C) with alternate feed conditions of variable duration. The cycled CO2 adsorption and methanation were also investigated by in-situ DRIFT comparing results for xLi-Ru/Al2O3 materials against the reference Ru/Al2O3 catalyst. The favourable synergism existing at the nanoscale between the Li-aluminate sorbent phase and the catalytic Ru sites enhances the intrinsic activity of the DFMs that can guarantee high methane productivity and selectivity with low noble metal loadings.