MnO2 Loading Research Articles

Degradation of magenta dye using cavitation-based transducers to glass marble: Lab to semi-pilot scale operations.

In the present work, the degradation of magenta dye has been investigated using ultrasonic (US) and ultraviolet (UV) irradiation at a laboratory scale. Additionally, the investigation was conducted at a semi-pilot scale by employing hydrodynamic cavitation and a novel air-marble cavitation reactor. Initially, optimization studies such as the effect of initial dye concentration and catalyst loading of TiO2 and MnO2 followed by the effect of combined catalyst loading (TiO2 /MnO2 ) on the extent of degradation have been studied at a capacity of 3 L. It was observed that the US irradiation results in 87.1% and 68.2% of degradation, whereas the UV irradiation results in 79.8% and 56.4% extent of degradation at 1 g/l of TiO2 and 0.8 g/l of MnO2 , respectively. The maximum degradation was 92.1% at the combined loading of 0.6 g/l (1:0.8; TiO2 :MnO2 ) using US irradiation with a capacity of 3L and 81.3% using a hydrodynamic cavitation reactor with a semi-pilot scale capacity of 7L. The chemical oxygen demand (COD) analysis also showed the highestCODremoval of 92% at a small scale using the US irradiation and 76% at a semi-pilot scale using hydrodynamic cavitation. On a small scale, the cost of a US/TiO2 + MnO2 treatment scheme is US$ 0.01/L, whereas on a semi-pilot scale using HC/TiO2 + MnO2 , the cost is US$ 0.04/L. Both of these treatment schemes offer viable pathways for degradation based on energy and economic assessments. Overall, the current work has clearly demonstrated the effectiveness of the cavitational reactor for the efficient degradation of magenta dye from lab to semi-pilot scale operation. PRACTITIONER POINTS: Small-scale dye containing wastewater treatment using ultrasound and ultraviolet irradiation Combined use of catalysts at large-scale operations with novel cavitation techniques Novel cavitation techniques studied for dye degradation. Energy efficiency and cost analysis evaluated for AOPs studies.

Highly effective mineralization of acetic acid wastewater via catalytic ozonation over the promising MnO2/γ-Al2O3 catalyst

The complete mineralization of acetic acid in wastewater through a biodegradation process is difficult due to the α-position methyl coordinated with the carboxyl group, and this work explored the oxidation performance of acetic acid by catalytic ozonation with metal oxides supported on γ-Al2O3. It was found that MnO2/γ-Al2O3 catalyst achieved superior mineralization performance to Co/Fe/CeOx supported on γ-Al2O3 for acetic acid wastewater treatment. The effects of MnO2 loading, catalyst dosage, acetic acid concentration, O3 concentration, ozonation temperature, and initial pH value of the acetic acid solution were investigated. Typically, the mineralization of acetic acid over 1.0 wt.% MnO2/γ-Al2O3 catalyst was as high as 88.4% after 300 min ozonation of 1.0 g·L‒1 acetic acid at 25 °C with the highest energy efficiency around 15 g·kWh‒1. By contrast, the mineralization of acetic acid could only reach 43.2% in the absence of the catalyst, with an energy efficiency of 5.1 g·kWh−1. Radical quenchers and indicated that ·OH radical, O2− species originated from ozone played an important role in the catalytic ozonation of acetic acid into CO2 and H2O. Besides, the catalytic ozonation mechanism of acetic acid over MnO2/γ-Al2O3 was carefully proposed based on the in situ DRIFTS results.

Enhancement of activity and lifetime of nano-iron oxide catalyst for environmentally friendly catalytic phenol oxidation process

The amount and characteristics of wastewater produced are determined by the process configuration. Refineries produce contaminated effluent of phenol levels up to 300–600 mg/L. For wet oxidation of phenol, multiloading and multifunctional MnO2/Fe2O3 were utilized in the present study to develop a cost-effective nanocatalyst to clean refinery wastewater at a high rate of phenol removal and a long lifetime of catalyst activity. The catalysts were doped with two different loading of 2% and 5% of MnO2. For full oxidation of carcinogenic phenolic compounds into the unharmful CO2 and H2O, the catalytic breakdown of H2O2 as an oxidation agent produces oxygen bubbles and hydroxyl radicals. The prepared catalysts were evaluated in a batch reactor and the results showed that the loading of MnO2 over the Fe2O3 has a positive impact on the oxidation of phenol as increasing the MnO2 loading increased the rate of phenol oxidation and did not result in the deactivation of the available catalyst pores. The highest conversion of phenol achieved was 94 wt% at 80 min and 75 °C over the 5% MnO2/Fe2O3 catalyst. Also, it was observed that the prepared catalyst sustained the deactivation for several cycles of catalytic oxidation of phenol as the catalyst activity remained almost constant as time proceeds to 120 min.

Mechanically Improved Zn-Ion Battery Cathodes Based on Branched Aramid Nanofibers

Zinc-ion batteries address common environmental and safety concerns by using nontoxic and abundant metals in conjunction with aqueous electrolytes. Nonetheless, for applications such as structural energy storage, where a multifunctional system aims to replace both the structural and energy storage subsystems of an electric vehicle, safe but mechanically strong components are desired. MnO2, a typical cathode material for Zn-ion batteries, however, exhibits poor mechanical performance. Therefore, a lack of knowledge remains for mechanically strong cathodes for safe, structural Zn-ion batteries. Here, we combine branched aramid nanofibers (BANFs) with MnO2 particles and reduced graphene oxide (rGO) to fabricate mechanically improved cathodes for Zn-ion batteries. The addition of BANFs allows for an increase in the MnO2 loading and significantly improved electrochemical properties (up to 190% increase of capacity). Additionally, hydrogen bonding between BANFs and rGO notably improved the mechanical properties (up to 51% increase in ultimate tensile strength and up to 593% increase in ultimate strain). Electrochemo-mechanical tests were also performed to assess coupling, showing that applied strain decreases the capacity, but no measurable internal stresses develop during electrochemical cycling. This work combines the multifunctionality of structural electrodes with the inherent safety of Zn-ion batteries.

Construction of polyaniline/MnO2 core-shell nanocomposites in carbonized wood tracheids for high-performance all-solid-state asymmetric supercapacitors

Polyaniline (PANI) nanomaterials or carbon nanotubes (CNTs) are first synthesized on the tracheid wall of activated wood carbon (AWC) to obtain PANI@AWC and CNT@AWC, respectively. Then MnO2 nanosheets are electrodeposited on the outer surface of the PANI nanomaterials to form a core-shell structure. The introduction of PANI in wood tracheids not only increases the loading of MnO2, but also improves the electrical conductivity and structural stability, and the core-shell structure can synergistically store energy. Then using the MnO2/PANI@AWC composite electrode as an anode and using CNT@AWC as a cathode, a high-performance all-solid-state asymmetric supercapacitor with high energy density and high cycling stability is successfully constructed. This supercapacitor has a wide working voltage of 0–1.8 V and a high energy density of 0.875 mWh cm−2 at 9 mW cm−2. The capacitance retention rate is as high as 93.21 % after 10,000 charge-discharge cycles. Therefore, wood-based composites with aligned tracheids have great potential in the development of high-power and high-energy-density energy storage devices.

A cancer cell membrane coated nanoparticles-based gene delivery system for enhancing cancer therapy

Gene therapy is a superior therapeutic means in cancer therapy. However, the instability of nucleic acid and the lack of suitable delivery carrier greatly restricts its further development and application. Herein, we coupled low molecular weight polyethyleneimine (LMW PEI) through disulfide bonds, then modified it with manganese dioxide (MnO2) nanosheets and nuclear localization signal peptide (NLS), as a p53 gene carrier, and finally coated it with B16F10 cell membrane to construct a novel gene-carrier system CM@MnO2-PEI-NLS-ss/p53 (M@MPNs/p53). Tumor cell membrane coating endows nanoparticles with homotypic targeting and immune escape capabilities, disulfide-crosslinked LMW-PEI has high transfection efficiency and low toxicity, and NLS peptides enhance nuclear delivery and improve p53 gene delivery efficiency; meanwhile, MnO2 nanosheets oxidize high intracellular concentration of glutathione (GSH), sensitizing p53 gene-mediated antitumor therapy. The results showed that the novel biofilm-camouflaged M@MPNs/p53 nanoparticles had a highly specific targeting effect on homologous cancer cells and could effectively inhibit tumor growth in vitro and in vivo. Besides, MnO2 loading improved p53-mediated tumor regression. This novel gene delivery platform is of great significance in improving gene delivery efficiency and enhancing anti-tumor therapy.

Molecular deciphering of hydrophobic, Zinc-philic and robust Amino-functionalized Polysilane for Dendrite-free Zn Anode

As one of most prospective anode materials of aqueous batteries, Zn metal faces severe electrolyte corrosion and fatal dendrite growth. To address these issues, the electrolyte/Zn interface needs to be carefully engineered. Here, a dense and robust layer of polysilane functionalized by -NH2 is coated on Zn in a new way. In this layer, -NH2 provides adequate alkalinity and important interaction with Zn2+, enhancing the hydrolysis and regulating the Zn2+ flux. Propyl groups increase the flexibility to buffer inevitable strain/stress and the hydrophobicity to reduce the permeation of water. Si-O-Zn enables the durable interface between Zn and this layer. These results lead to superior mechanical property, suppressed side reactions and uniform plating/stripping. Hence, it shows excellent electrochemical performance, ∼300 hours at 20 mA cm-2 for 10 mAh cm-2 (Depth of Discharge ∼57%) in symmetrical cells, and average Coulombic efficiency of 99.8% during 800 cycles for 3 mAh cm-2 in asymmetrical cells. Even at a high loading of MnO2, a small N/P ratio and a limited electrolyte, the full cells coupled still display a capacity of ∼2.93 mAh cm-2 after 100 cycles at 0.5 C.

Interface Engineering of Aqueous Zinc/Manganese Dioxide Batteries with High Areal Capacity and Energy Density.

Commercialization of aqueous batteries is mainly hampered by their low energy density, owing to the low mass loading of active cathode materials. In this work, a MnO2 cathode structure (MnO2 /CTF) is designed to modify the MnO2 /collector interface for enhanced ion transportation properties. Such a cathode can achieve ultrahigh mass loading of MnO2 , large areal capacity, and high energy density, with excellent cycling stability and rate performance. Specifically, a 0.15mm thick MnO2 /CTF cathode can realize a mass loading of 20mg cm-2 with almost 100% electrochemical conversion of MnO2 , providing the maximum areal capacity of 12.08mA h cm-2 and energy density of 191W h kg-1 for Zn-MnO2 /CTF batteries when considering both cathode and anode. Besides the conventional low energy demonstrations, such a Zn-MnO2 /CTF battery is capable of realistic applications, such as mobile phones inourdaily life, which is a promising alternative for wearable electronics.

Capacitive removal of Pb ions via electrosorption on novel willow biochar–manganese dioxide composites

ABSTRACT Biochar derived from lignocellulosic biomass has been used as a low-cost adsorbent in wastewater treatment applications. Due to its rich porous structure and good electrical conductivity, biochar can be used as a cost-effective electrode material for capacitive deionization of water. In this work, willow biochar was prepared through carbonization of shrub willow chips, activated with potassium hydroxide, and loaded with manganese dioxide (WBC-K-MnO2 nanocomposite). The prepared materials were used to electrochemically adsorb Pb2+ from aqueous solutions. Under the applied potential of 1.0 V, the WBC-K-MnO2 electrode exhibited a high Pb2+ specific electrosorption capacity (23.3 mg/g) as compared to raw willow biochar (4.0 mg/g) and activated willow biochar (9.2 mg/g). KOH activation followed by MnO2 loading on the surface of raw biochar enhanced its BET surface area (178.7 m2/g) and mesoporous volume ratio (42.1%). Moreover, the WBC-K-MnO2 nanocomposite exhibited the highest specific capacitance value of 234.3 F/g at a scan rate of 5 mV/s. The electrosorption isotherms and kinetic data were well explained by the Freundlich and pseudo-second order models, respectively. The WBC-K-MnO2 electrode demonstrated excellent reusability with a Pb2+ electrosorption efficiency of 76.3% after 15 cycles. Thus, the WBC-K-MnO2 nanocomposite can serve as a promising candidate for capacitive deionization of heavy metal contaminated water.

Remediation of Soil Mercury by Modified Vermiculite-Montmorillonite and Its Effect on the Growth of Brassica chinensis L.

In this study, the surface of vermiculite-montmorillonite was modified by MnO2 loading. The modified vermiculite-montmorillonite was added to remediate the potentially toxic trace element (PTE) Hg present in soil containing coal gangue. Pot experiments were conducted to analyze and compare the pH values, Hg contents and Hg species present in coal gangue-containing soil, with and without the modified materials added, to determine whether the addition of modified materials had an effect on the growth of Brassica chinensis L. Results showed that with the addition of 35 g·kg−1 modified vermiculite-montmorillonite, the pH of soil increased by a value of 0.79, compared with that in the control group. When 15 g·kg−1 was added, the concentration of Hg in soil decreased by 98.2%. The addition of modified materials promoted the transformation of Hg in soil from a bioavailable form to an unavailable form; that is, the content of the residual form increased. The plant height and biomass of Brassica chinensis L. also increased, which indicated that the addition of modifiers can increase soil productivity, reduce the effects of PTEs on organisms in soil, and promote plant growth. Therefore, the addition of modified vermiculite-montmorillonite can achieve remediation of coal gangue-containing soil.

Rational Construction of Yolk-Shell Bimetal-Modified Quinonyl-Rich Covalent Organic Polymers with Ultralong Lithium-Storage Mechanism.

Covalent organic polymers are attracting more and more attention for energy storage devices due to their lightweight, molecular viable design, stable structure, and environmental benignity. However, low charge-carrier mobility of pristine covalent organic materials is the main drawback for their application in lithium-ion batteries. Herein, a yolk-shell bimetal-modified quinonyl-rich covalent organic material, Co@2AQ-MnO2, has been designed and synthesized by in situ loading of petal-like nanosized MnO2 and coordinating with Co centers, with the aim to improve the charge conductivity of the covalent organic polymer and activate its Li-storage sites. As investigated by in situ FT-IR, ex situ XPS, and electrochemical probing, the quinonyl-rich structure provides abundant redox sites (carbonyl groups and π electrons from the benzene ring) for lithium reaction, and the introduction of two types of metallic species promotes the charge transfer and facilitates more efficient usage of active energy-storage sites in Co@2AQ-MnO2. Thus, the Co@2AQ-MnO2 electrode exhibits good cycling performance with large reversible capacity and excellent rate performance (1534.4 mA h g-1 after 200 cycles at 100 mA g-1 and 596.0 mA h g-1 after 1000 cycles at 1000 mA g-1).

Fabrication and tribological behavior of MnO2/epoxy nanocomposites

Tribology is the study of moving surfaces, and it has a variety of effects on our lives. From an economic point of view, wear is one of the most important aspects of an industry’s viability. Parts of the machine can wear out, and they need to be replaced. This is especially important for polymer-based materials. Therefore, it is important to reduce maintenance costs and improve machine reliability in a variety of engineering applications through proper material selection. The present investigation deals with the fabrication of manganese dioxide (MnO2)/epoxy nanocomposite and investigates its tribological properties. The MnO2/epoxy nanocomposites were fabricated via a solution mixing technique. The phase identification and surface morphology of the sample was examined by X-ray diffractometer and field emission scanning electron microscope, respectively. The mass density, micro-hardness, and specific wear rate data of samples revealed that the mass density, micro-hardness, and wear resistance of the samples increased with the addition of MnO2 in the epoxy matrix. The nanocomposite sample containing 0.5 wt. % MnO2 loading in the epoxy matrix shows higher density, micro-hardness, and wear resistance compared to other samples. The result also shows that with the addition of MnO2 in the epoxy matrix, the coefficient of friction of the samples is increased. The percentage reduction in specific wear rate due to the addition of 0.5 wt. % MnO2 in neat epoxy is 68.10%, whereas the percentage increase in the coefficient of friction is 19.30%. The results of the analysis of variance show the effect of adding wt. % of MnO2 in the epoxy matrix is significant in the tribological responses. The worn surface analysis shows that the fatigue wear mode seems to be the dominating mode of wear for all samples as compared to the other modes of wear. The properties of MnO2/epoxy nanocomposite data revealed that the developed material may be used in the automotive industry as a structural material, fabrication of snow sled, ball bearing housing, or plastic gear materials with adequate lubrication.

Harnessing Adsorption–Catalysis Synergy: Efficient Oxidative Removal of Gaseous Formaldehyde by a Manganese Dioxide/Metal–Organic Framework Nanocomposite at Room Temperature

AbstractThe potential utility of a transition metal oxide/metal–organic framework (MOF) nanocomposite has been explored using manganese dioxide (MnO2)/Universitetet i Oslo (UiO)‐66‐amine (NH2 (prototypical zirconium (Zr) MOF)) to develop an efficient adsorption–catalysis system for the removal of formaldehyde (FA) from the air. The room‐temperature FA (100 ppm) conversion (XFA (%)), when tested using five different MnO2 (wt%) loadings in the nanocomposite, is estimated as: 1% MnO2 (88%) > 2% MnO2 (86%) > 4% MnO2 (84%) > 6% MnO2 (75%) > 20% MnO2 (47%). The FA removal performance is lowered as the active catalytic sites are covered with the increases in the MnO2 loading (e.g., >1 wt%). The FA and molecular oxygen species preferably adsorb (and activate) onto the Zr atoms attached to the NH2 groups. The oxidation of FA into carbon dioxide proceeds subsequently through the formation of intermediates (e.g., dioxymethylene and formate). The MnO2 nanoclusters act as secondary reactive adsorption sites to boost the capture, activation, and oxidation of the FA molecules at the Zr active centers. Accordingly, the MnO2/UiO‐66‐NH2 nanocomposite is demonstrated to effectively harness the adsorption–catalysis synergy for highly efficient removal of FA relative to other well‐known catalysts (e.g., platinum and metal oxide‐based nanomaterials).

Block Copolymer‐Derived Porous Carbon Fibers Enable High MnO2 Loading and Fast Charging in Aqueous Zinc‐Ion Battery

AbstractRechargeable aqueous Zn−MnO2 batteries are promising for stationary energy storage because of their high energy density, safety, environmental benignity, and low cost. Conventional gravel MnO2 cathodes have low electrical conductivity, slow ion (de‐)insertion, and poor cycle stability, resulting in poor recharging performance and severe capacity fading. To improve the rechargeability of MnO2, strategies have been devised such as depositing micrometer‐thick MnO2 on carbon cloth and blending nanostructured MnO2 with additives and binders. The low electrical conductivity of binders and sluggish ion (de‐)insertion in micrometer‐thick MnO2, however, still limit the fast‐charging performance. Herein, we have prepared porous carbon fiber (PCF) supported MnO2 cathodes (PCF@MnO2), comprised of nanometer‐thick MnO2 uniformly deposited on electrospun block copolymer‐derived PCF that have abundant uniform mesopores. The high electrical conductivity of PCF, fast electrochemical reactions in nanometer‐thick MnO2, and fast ion transport through porous nonwoven fibers contribute to a high rate capability at high loadings. PCF@MnO2, at a MnO2 loading of 59.1 wt %, achieves a MnO2‐based specific capacity of 326 and 184 mAh g−1 at a current density of 0.1 and 1.0 A g−1, respectively. Our approach of block copolymer‐based PCF as a support for zinc‐ion cathode inspires future designs of fast‐charging electrodes with other active materials.

Co‐Hydrothermal Carbonization of Cotton Stalks and MnO2 for Direct Solar Steam Generation with High Efficiency

Biomass‐based photothermal materials for solar steam power generation have been a recent research hotspot. However, despite the many research advances that have been made, many challenges remain. For example, high temperature carbonization leads to the loss of hydrophilicity, the surface coating is easy to peel off, hydrothermal carbonization (HTC) does not guarantee the photothermal performance, and hydrothermal carbonization fluid (HTC‐F) is difficult to handle. Herein, a new material (H‐CS/MnO2) is prepared by co‐hydrothermal carbonization of cotton stalks (CS) and MnO2, and a stable and effective evaporation system is designed. While both ensure super hydrophilicity, the stable loading of MnO2 leads to an excellent photothermal performance. Experimental results show that H‐CS/MnO2 reaches 93.46% evaporation efficiency and the evaporation rate can reach 2.43 kg m−2 h−1 under 1 sun. Moreover, by means of recycling, not only the treatment of HTC solution is solved, but also the carbon dots are continuously enriched and exhibit certain photothermal effects during the recycling process. In addition, H‐CS/MnO2 exhibited excellent salt resistance and corrosion resistance. The obtained condensate heavy ion concentration removal rate reached more than 99.9%. Therefore, the H‐CS/MnO2 fabricated herein has the possibility of practical application in the future.

High-performance hierarchical MnO2/CNT electrode for multifunctional supercapacitors

Supercapacitors possessing multiple functions other than storing energy, such as bearing mechanical loads, are a promising technology for a wide range of applications. However, achieving both energy storage efficiency and mechanical strength/stiffness requires structurally strong electrolytes and high-capacitance electrodes. Herein, we report a novel method of synthesizing a high-mass loading of MnO2 on carbon nanotube (CNT) mats to create nanocomposite electrodes of high capacitance and mechanical properties. With CNTs acting as structural reinforcement for the pseudocapacitive MnO2 matrix, the resulting nanocomposite electrodes exhibited an ultrahigh areal capacitance of 2579 mF/cm2 at a current density of 1 mA/cm2 and excellent mechanical properties. These electrodes were then used to fabricate flexible and mechanically strong structural supercapacitors by infusing with a PVA gel electrolyte and a PEGDGE solid electrolyte, respectively. The resulting flexible supercapacitors yielded a high areal capacitance of 947 mF/cm2 while the structural supercapacitors gave a high tensile modulus of 6.1 GPa. These results demonstrated that the hierarchical MnO2/CNT electrodes could provide both excellent energy storage capability and structural stiffness and strength, expanding their applications beyond mono-functional supercapacitors.

Comprehensive study to ascertain the effect of MnO2 loading on supercapacitive properties of conducting polymers

This study reports the electrochemical properties of Manganese dioxide (MnO2) with four types of conducting polymers such as polyaniline (PANi), polythiophene (PTh), polypyyrole, and polyindole (PIn) by preparing their composites. All four conducting polymers were prepared by chemical oxidative polymerization approach. The prepared composites were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Raman spectroscopy, ultra–violate visible (UV–VIS) spectroscopy, and photoluminance (PL). Similarly, the supercapacitive properties such, cyclic voltammetry (CV) curve, capacitance retention and cycle stability of composite materials were investigated. The highest value of specific capacitance was obtained for MnO2-PANi (Mn-PANi) composite, which was found to be 633.75 Fg−1.

Characterizing the impact of MnO2 addition on the efficiency of Fe0/H2O systems

The role of manganese dioxide (MnO2) in the process of water treatment using metallic iron (Fe0/H2O) was investigated in quiescent batch experiments for t ≤ 60 d. MnO2 was used as an agent to control the availability of solid iron corrosion products (FeCPs) while methylene blue (MB) was an indicator of reactivity. The investigated systems were: (1) Fe0, (2) MnO2, (3) sand, (4) Fe0/sand, (5) Fe0/MnO2, and (6) Fe0/sand/MnO2. The experiments were performed in test tubes each containing 22.0 mL of MB (10 mg L−1) and the solid aggregates. The initial pH value was 8.2. Each system was characterized for the final concentration of H+, Fe, and MB. Results show no detectable level of dissolved iron after 47 days. Final pH values varied from 7.4 to 9.8. The MB discoloration efficiency varies from 40 to 80% as the MnO2 loading increases from 2.3 to 45 g L−1. MB discoloration is only quantitative when the operational fixation capacity of MnO2 for Fe2+ was exhausted. This corresponds to the event where adsorption and co-precipitation with FeCPs is intensive. Adsorption and co-precipitation are thus the fundamental mechanisms of decontamination in Fe0/H2O systems. Hybrid Fe0/MnO2 systems are potential candidates for the design of more sustainable Fe0 filters.

Synergistic enhanced catalysis of micro-reactor with nano MnO2/ZIF-8 immobilized in membrane pores by flowing synthesis

A catalytic membrane micro-reactor (CMMR) with nano MnO2/ZIF-8 immobilized in membrane pores has been fabricated by flowing synthesis and formaldehyde degradation was used to test its catalytic performance. The CMMR with deep-permeation nano structure (DPNS) has good stability, uniform nano MnO2/ZIF-8 dispersion and higher loading capacity. The MnO2 coated on the surface of nano ZIF-8 with the size in the range of 100–150 nm was obtained. The contact between formaldehyde and MnO2 is enhanced by the effect of even disperse of membrane pores. The enhanced mass transfer can be achieved in the micro-scale pores of the membrane by the confined space effect. A higher amount of MnO2 loading and higher formaldehyde absorption rate can be achieved by the effect of ZIF-8 in membrane pores. The formaldehyde degradation rate was increased from 82.6% to 94.0%, if the MnO2 loading capacity was increased from 98 mg g−1 to 344 mg g−1.

Co-Hydrothermal Carbonization Of Cotton Stalks and MnO <sub>2</sub> For Direct Solar Steamgeneration With High Efficiency

Biomass-based photothermal materials for solar steam power generation have been a recent research hotspot. However, despite the many research advances that have been made, many challenges remain. For example, high temperature carbonization leads to the loss of hydrophilicity, the surface coating is easy to peel off, hydrothermal carbonization (HTC) does not guarantee the photothermal performance, and hydrothermal carbonization fluid (HTC-F) is difficult to handle. In this paper, a new material (H-CS/MnO2) was prepared by co-hydrothermal carbonization of cotton stalks (CS) and MnO2, and a stable and effective evaporation system was designed. While both ensure super hydrophilicity, the stable loading of MnO2 leads to excellent photothermal performance. Moreover, by means of recycling, not only the treatment of hydrothermal carbonization solution is solved, but also the CDs are continuously enriched and exhibit certain photothermal effects during the recycling process. In addition, H-CS/MnO2 exhibited excellent salt resistance and corrosion resistance.