Tunable Impedance of Cobalt Loaded Carbon for Wide-Range Electromagnetic Wave Absorption.

Impedance matching modulation of the electromagnetic wave (EMW) absorbers toward broad effective absorption bandwidth (EAB) is the ultimate aim in EMW attenuation applications. Here, a Joule heating strategy is reported for preparation of the Co-loaded carbon (Co/C) absorber with tunable impedance characteristics. Typically, the size of the Co can be regulated to range from single-atoms to clusters, and to nanocrystals. The varied sizes of the Co combined with different graphitization degrees of carbon can result in different relative input impedances and electromagnetic loss, leading to the tunable EMW absorption properties of the Co/C absorber. By meticulously coalescing the different prepared Co/C, the working frequency can be easily tuned, covering Ku, X, and C bands. Furthermore, the Co/C demonstrates a high EMW attenuation due to its unique dielectric loss capability and magnetic loss characteristics. The abundant interfaces of Co/C can also contribute to the enhanced interfacial polarization for improving EMW attenuation. This work demonstrates the importance of optimizing the metal and carbon interaction to the impedance matching toward wide EAB of the EMW absorbers.

Glass-Blowing-Inspired Upcycling of Thermosetting Polymer to Neuron-Like Hierarchical Carbon for Microwave Absorption and Conversion.

Upgrading thermosetting polymer waste and harvesting unwanted electromagnetic energy are of great significance in solving environmental pollution and energy shortage problems. Herein, inspired by the glass-blowing art, a spontaneous, controllable, and scalable strategy is proposed to prepare hollow carbon materials by inner blowing and outside blocking. Specifically, hierarchically neuron-like hollow carbon materials (HCMSs) with various sizes are fabricated from melamine-formaldehyde sponge (MS) waste. Benefiting from the synergistic of the hollow "cell body" and the connected "protrusions" networks, HCMSs reveal superior electromagnetic absorption performance with a strong reflection loss of -54.9 dB, electromagnetic-heat conversion ability with a high conversion efficiency of 34.4%, and efficient energy storage performance in supercapacitor. Furthermore, a multifunctional device integrating electromagnetic-heat-electrical energy conversion is designed, and its feasibility is proved by experiments and theoretical calculations. The integrated device reveals an output voltage of 34.5 mV and a maximum output power of 0.89 µW with electromagnetic radiation for 60 s. This work provides a novel solution to recycle polymer waste, electromagnetic energy, and unwanted thermal energy.

Aerobically Autoxidized Self-Charge Concept Derived from Synergistic Pyrrolic Nitrogen and Catechol Configurations in N, O Co-Doped Carbon Cathode Material.

Aerobically autoxidized self-charging concept has drawn significant attraction due to its promising chemical charge features without external power supply. Particularly, heteroatom-doped carbon materials with abundant oxidizable sites and good conductivity are expected to be ideal cathode materials. However, there is no well-defined aerobically autoxidized self-charging concept based on heteroatom-doped carbon materials, significantly hindering the design of related carbon cathodes. An aerobically autoxidized self-chargeable concept derived from synergistic effect of pyrrolic nitrogen and catechol configuration in carbon cathode using model single pyrrolic nitrogen and oxygen (N-5, O) co-doped carbon and O-enriched carbon is proposed. First, self-charging of N-5, O co-doped carbon cathode can be achieved by aerobic oxidation of pyrrolic nitrogen and catechol to oxidized pyrrolic nitrogen and ortho-quinone configurations, respectively. Second, introducing a single pyrrolic nitrogen configuration enhanced acidic wettability of N-5, O co-doped carbon facilitating air self-charge/galvanic discharge involving proton removal/introduction. Third, synergistic effect of pyrrolic nitrogen and hydroxyl species with the strong electron-donating ability to conjugated carbon-based backbone endows N-5, O co-doped carbon with a higher highest occupied molecular orbital (HOMO) energy level more susceptible to oxidation charging. The assembled Cu/Carbon batteries can drive a timer after every air-charging run. This promising aerobically autoxidized self-charging concept can inspire exploring high-efficiency self-charging devices.

Degradation of thiocyanate by Fe/Cu/C microelectrolysis: Role of pre-magnetization and enhancement mechanism.

Thiocyanate (SCN-), a non-volatile inorganic pollutant, is commonly found in various types of industrial wastewater, which is resistant to hydrolysis and has the potential to be toxic to organisms. Premagnetized iron-copper-carbon ternary micro-electrolytic filler (pre-Fe/Cu/C) was prepared to degrade SCN-. Pre-Fe/Cu/C exhibited the most significant enhancement effect on SCN- removal when magnetized for 5 min with an intensity of 100 mT, and the SCN- removal rate was the highest at an initial pH of 3.0 and an aeration rate of 1.6 L/min. The electrochemical corrosion and electron transfer in the pre-Fe/Cu/C system were confirmed through SEM, XPS, FTIR, XRD, and electrochemical tests. This resulted in the formation of more corrosion products and multiple cycles of Fe2+/Fe3+ and Cu0/Cu+/Cu2+. Additionally, density functional theory (DFT) calculations and electron paramagnetic resonance (EPR) were utilized to illustrate the oxygen adsorption properties of the materials and the participation of reactive oxygen species (1O2, ·O2-, and ·OH) in SCN- removal. The degradation products of SCN- were identified as SO42-, HCO3-, NH4+, and N2. This study introduced the use of permanent magnets for the first time to enhance Fe/Cu/C ternary micro-electrolytic fillers, offering a cost-effective, versatile, and stable approach that effectively effectively enhanced the degradation of SCN-.

Metal-Free Wet Chemistry for the Fast Gram-Scale Synthesis of γ-Graphyne and its Derivatives.

γ-Graphyne (GY), an emerging carbon allotrope, is envisioned to offer various alluring properties and broad applicability. While significant progress has been made in the synthesis of GY over recent decades, its widespread application hinges on developing efficient, scalable, and accessible synthetic methods for the production of GY and its derivatives. Here we report a facile metal-free nucleophilic crosslinking method using wet chemistry for fast gram-scale production of GY and its derivatives. This synthesis method involves the aromatic nucleophilic substitution reactions between fluoro-(hetero)arenes and alkynyl silanes in the presence of a catalytic amount of tetrabutylammonium fluoride, where the fluoride plays a crucial role in removing protective groups from alkynyl silanes and generating reactive alkynylides. Our comprehensive analysis of the as-prepared GY reveals a layered structure, characterized by the presence of the C(sp)-C(sp2) bond. The synthetic strategy shows remarkable tolerance to various functional groups and enables the preparation of diverse F-/N-rich GY derivatives, using electron-deficient fluoro-substituted (hetero)arenes as precursors. The feasibility of producing GY and derivatives from fluorinated (hetero)arenes through the metal-free, scalable, and cost-effective approach paves the way for broad applications of GY and may inspire the development of new carbon materials.

Carboxylated Hexagonal Boron Nitride/Graphene Configuration for Electrosynthesis of High-Concentration Neutral Hydrogen Peroxide.

The electrosynthesis of hydrogen peroxide (H2 O2 ) via two-electron (2e- ) oxygen (O2 ) reduction reaction (ORR) has great potential to replace the traditional energy-intensive anthraquinone process, but the design of low-cost and highly active and selective catalysts is greatly challenging for the long-term H2 O2 production under industrial relevant current density, especially under neutral electrolytes. To address this issue, this work constructed a carboxylated hexagonal boron nitride/graphene (h-BN/G) heterojunction on the commercial activated carbon through the coupling of B, N co-doping with surface oxygen groups functionalization. The champion catalyst exhibited a high 2e- ORR selectivity (>95 %), production rate (up to 13.4 mol g-1 h-1 ), and Faradaic efficiency (FE, >95 %). The long-term H2 O2 production under the high current density of 100 mA cm-2 caused the cumulative concentration as high as 2.1 wt %. The combination of in situ Raman spectra and theoretical calculation indicated that the carboxylated h-BN/G configuration promotes the adsorption of O2 and the stabilization of the key intermediates, allowing a low energy barrier for the rate-determining step of HOOH* release from the active site and thus improving the 2e- ORR performance. The fast dye degradation by using this electrochemical synthesized H2 O2 further illustrated the promising practical application.

Fe-O4 Motif Activated Graphitic Carbon via Oxo-Bridge for Highly Selective H2O2 Electrosynthesis.

Carbon-based materials have been utilized as effective catalysts for hydrogen peroxide electrosynthesis via two-electron oxygen reduction reaction (2e ORR), however the insufficient selectivity and productivity still hindered the further industrial applications. In this work, we report the Fe-O4 motif activated graphitic carbon material which enabled highly selective H2O2 electrosynthesis operating at high current density with excellent anti-poisoning property. In the bulk production test, the concentration of H2O2 cumulated to 8.6 % in 24 h and the corresponding production rate of 33.5 mol gcat -1 h-1 outperformed all previously reported materials. Theoretical model backed by in situ characterization verified α-C surrounding the Fe-O4 motif as the actual reaction site in terms of thermodynamics and kinetics aspects. The strategy of activating carbon reaction site by metal center via oxo-bridge provides inspiring insights for the rational design of carbon materials for heterogeneous catalysis.

Selective capture of palladium from acid wastewater by thiazole-modified activated carbon: Performance and mechanism.

As a kind of scarce metal, palladium is widely used in many chemical industries. It essential to recover palladium from secondary resources, especially acidic media, owing to high content of palladium in secondary wastes and widespread extraction of palladium via strong acids. Chemically modified carbon materials not only have the advantage of activated carbon but also achieve the precise removal of specific pollutants, which is a kind of adsorption material with broad application prospects. In this direction, we report a solid carbon material named AT-C, which is obtained by one-step synthesis of 2-aminothiazoles grafted to the carbon surface by amidation. The present adsorbent delivers a high palladium adsorption capacity of 178.9 mg g-1, and desirable thermal and chemical stability. The uniform presence of abundant sulfur atoms and CO in the porous network enables AT-C to achieve selective absorption and rapid adsorption kinetics of Pd2+ in the complex water mixture containing many competing ions in the acidic pH range. For the strongly acidic leachates of catalysts, AT-C exhibits outstanding stability in cyclic experiments. Meanwhile, the fixed-bed column test indicates that 1076 bed volumes of the feeding streams can be effectively treated. In addition, AT-C exhibits superior adsorption selectivity, and the recovery efficiency of Pd2+ in actual industrial wastewater is 96.6%. This work realizes an efficient, rapid, and selective removal of palladium under acidic conditions, and provides a reference for complex industrial water treatment and resource recovery of precious metals.

Cobalt and nitrogen co-doped monolithic carbon foam for ultrafast degradation of emerging organic pollutants via peroxymonosulfate activation.

Cobalt-based catalysts are expected as one of the most promising peroxymonosulfate (PMS) activators for the removal of organic pollutants from industrial wastewater. However, the easy agglomeration, difficult separation, and secondary pollution of cobalt ions limit their practical application. In this study, a novel, highly efficient, reusable cobalt and nitrogen co-doped monolithic carbon foam (Co-N-CMF) was utilized to activate PMS for ultrafast pollutant degradation. Co-N-CMF (0.2 g/L) showed ultrafast catalytic kinetics and higher total organic carbon (TOC) removal efficiency. Bisphenol A, ciprofloxacin, 2,4-dichlorophenoxyacetic acid, and 2,4-dichlorophenol could be completely degraded after 2, 4, 5, and 5 min, and the TOC removal efficiencies were 77.4 %, 68.9 %, 72.8 %, and 79.8 %, respectively, corresponding to the above pollution. The sulfate radical (SO4•-) was the main reactive oxygen species in Co-N-CMF/PMS based on electron paramagnetic resonance. The ecological structure-activity relationship program analysis via the quantitative structure activity relationship analysis and phytotoxicity assessment revealed that the Co-N-CMF/PMS system demonstrates good ecological safety and ecological compatibility. The Co-N-CMF catalyst has good catalytic activity and facile recycling, which provides a fine method with excellent PMS activation capacity for 2,4-dichlorophenol elimination from simulated industrial wastewater. This study provides new insights into the development of monolithic catalysts for ultrafast wastewater treatment via PMS activation.

Adsorption Studies on the Removal of Anionic and Cationic Dyes from Aqueous Solutions Using Discarded Masks and Lignin.

The carbon materials derived from discarded masks and lignin are used as adsorbent to remove two types of reactive dyes present in textile wastewater: anionic and cationic. This paper introduces the results of batch experiments where Congo red (CR) and Malachite green (MG) are removed from wastewater onto the carbon material. The relationship between adsorption time, initial concentration, temperature and pH value of reactive dyes was investigated by batch experiments. It is discovered that pH 5.0-7.0 leads to the maximum effectiveness of CR and MG removal. The equilibrium adsorption capacities of CR and MG are found to be 232.02 and 352.11 mg/g, respectively. The adsorption processes of CR and MG are consistent with the Freundlich and Langmuir adsorption models, respectively. The thermodynamic processing of the adsorption data reveals the exothermic properties of the adsorption of both dyes. The results show that the dye uptake processes follow secondary kinetics. The primary adsorption mechanisms of MG and CR dyes on sulfonated discarded masks and alkaline lignin (DMAL) include pore filling, electrostatic attraction, π-π interactions and the synergistic interactions between the sulphate and the dyes. The synthesized DMAL with high adsorption efficiency is promising as an effective recyclable adsorbent for adsorbing dyes, especially MG dyes, from wastewater.

Deactivation and Regeneration of Nitrogen Doped Carbon Catalyst for Acetylene Hydrochlorination.

The poor stability of carbon materials doped with nitrogen limited their development in acetylene hydrochlorination. Therefore, investigating the deactivation reasons of carbon catalysts and researching regeneration methods became the research focus. Herein, carbon-nitrogen materials were synthesized by one-step pyrolysis, which using biomass materials with high nitrogen content, the synthesized material was used in an acetylene hydrochlorination reaction. The acetylene conversion rate of D-GH-800 catalyst was up to 99%, but the catalytic activity decreased by 30% after 60 h reaction. Thermogravimetric analysis results showed that the coke content was 5.87%, resulting in catalyst deactivation. Temperature-programmed desorption verified that the deactivation was due to the strong adsorption and difficult desorption of acetylene by the D-GH-800 catalyst, resulting in the accumulation of acetylene on the catalyst surface to form carbon polymers and leading to the pore blockage phenomenon. Furthermore, based on the catalyst deactivation by carbon accumulation, we proposed a new idea of regeneration by ZnCl2 activation to eliminate carbon deposition in the pores of the deactivated catalyst. As a result, the activity of D-GH-800 was recovered, and lifetime was also extended. Our strategy illustrated the mechanism of carbon deposition, and the recoverability of the catalyst has promising applications.

Effectively Controlled Structures of Si-C Composites from Rice Husk for Oxygen Evolution Catalyst.

This work explores a simple way to regulate the morphology and structure of biomass-based carbon and effectively utilize its internal functional groups as the substrate for the next energy materials. The unique randomly oriented and highly interconnected cordyceps-like 3D structure of rice husk is formed by direct high-temperature carbonization, and the main component is SiC. The well-arranged cordyceps-like structure of SiC demonstrates a remarkable structural/chemical stability and a high rate of electron migration, and further could be used as a stable substrate for metal deposition and find application in the field of electrocatalysis. The oxygen evolution reaction catalyst (SiC-C@Fe3O4) prepared by chemical deposition exhibits a low overpotential (260 mV), low Tafel slope (56.93 mV dec-1), high electrochemical active surface area (54.92 mF cm-2), and low Rct value (0.15 Ω) at a current density of 10 mA cm-2 in 1 M KOH electrolyte. The produced natural Si-C composite materials overcome the limitations imposed by the intricate internal structure of silicon-rich biomass. The existence of this stable substrate offers a novel avenue for maximizing the utilization of rice-husk-based carbon, and broadens its application field. At the same time, it also provides a theoretical basis for the use of rice husks in the field of hydrogen production by electrolysis of water, thus promoting their high-value utilization.

Emerging Strategies for Enhancing Propionate Conversion in Anaerobic Digestion: A Review.

Anaerobic digestion (AD) is a triple-benefit biotechnology for organic waste treatment, renewable production, and carbon emission reduction. In the process of anaerobic digestion, pH, temperature, organic load, ammonia nitrogen, VFAs, and other factors affect fermentation efficiency and stability. The balance between the generation and consumption of volatile fatty acids (VFAs) in the anaerobic digestion process is the key to stable AD operation. However, the accumulation of VFAs frequently occurs, especially propionate, because its oxidation has the highest Gibbs free energy when compared to other VFAs. In order to solve this problem, some strategies, including buffering addition, suspension of feeding, decreased organic loading rate, and so on, have been proposed. Emerging methods, such as bioaugmentation, supplementary trace elements, the addition of electronic receptors, conductive materials, and the degasification of dissolved hydrogen, have been recently researched, presenting promising results. But the efficacy of these methods still requires further studies and tests regarding full-scale application. The main objective of this paper is to provide a comprehensive review of the mechanisms of propionate generation, the metabolic pathways and the influencing factors during the AD process, and the recent literature regarding the experimental research related to the efficacy of various strategies for enhancing propionate biodegradation. In addition, the issues that must be addressed in the future and the focus of future research are identified, and the potential directions for future development are predicted.

Research Progress on the Effects of Support and Support Modification on the FTO Reaction Performance of Fe-Based Catalysts.

In recent years, the non-petroleum production of light olefins has been the research focus of Fischer-Tropsch olefin synthesis (FTO). Iron-based catalysts have attracted much attention because of their low price, high catalytic activity, and wide temperature range. In this paper, traditional modification, hydrophobic modification, and amphiphobic modification of the catalyst are summarized and analyzed. It was found that traditional modification (changing the pore size and surface pH of the catalyst) will reduce the dispersion of Fe, change the active center of the catalyst, and improve the selectivity of light olefins (for example, SiO2: 32%). However, compared with functional methods, these traditional methods lead to poor stability and high carbon dioxide selectivity (for example, SiO2: 34%). Hydrophobic modification can inhibit the adsorption and retention of water molecules on the catalyst and reduce the local water pressure near the iron species in the nuclear layer, thus inhibiting the further formation of CO2 (for example, SiO2: 5%) of the WGSR. Amphiphobic modification can not only inhibit the WGSR, but also reduce the steric hindrance of the catalyst, increase the diffusion rate of olefins, and inhibit the reabsorption of olefins. Follow-up research should focus on these issues.

Nickel/nitrogen-doped carbon nanocomposites: Synthesis and electrochemical sensor for determination of p-nitrophenol in local environment.

A novel electrochemical sensor was prepared using N-doped carbon mesoporous materials supported with nickel nanoparticles (Ni-NCs) for environmental p-nitrophenol (p-NP) detection in a specific geographical area. These as-prepared Ni-NCs were dispersed in polyethyleneimine (PEI) solution and modified onto a glassy carbon electrode (GCE) for electrocatalytic reduction of p-NP. The Ni-NCs-PEI/GCE showed a high Faraday current at -0.302 V during p-NP reduction, because of the synergistic effect between Ni-NCs and PEI. Under ideal conditions, the Ni-NCs-PEI/GCE was used in the voltametric determination of p-NP, with high sensitivity. The linear ranges for p-NP are 0.06-10 µM and 10-100 µM with low detection limit (4.0 nM) and high sensitivity (1.465 µA µM-1 cm-2). In the presence of other phenolic compounds, this sensor showed good selectivity for p-NP detection. The Ni-NCs-PEI/GCE was also used to determine p-NP in environmental water samples of a specific geographical area, with recoveries ranging from 95.9% to 109.4%, and an RSD of less than 3.6%. Therefore, this novel Ni-NCs-PEI/GCE provides a good example for the design of other carbon-based nanocomposite materials, for electrochemical detection of trace p-NP in a specific geographical area.

Electrically Conductive and Antimicrobial Agro-Food Waste Biochar Functionalized with Zinc Oxide Particles.

Carbonaceous materials derived from biomass have been used as sustainable platforms for the growth of ZnO particles aiming the production of functional composite fillers. Kidney-bean pods were pyrolyzed by applying an experimental design that demonstrates that the specific surface area (SBET) of biochar is improved with increasing pyrolysis temperature combined with a short air-oxidation time. Meanwhile, the graphitization degree and the electrical conductivity (EC) of biochars were negatively affected by increasing the air-oxidation time. The biochar sample with the higher EC and the one with the higher SBET were selected to be functionalized with ZnO particles by a solvothermal methodology, obtaining composites with an EC and SBET properties superior to the ZnO-rGO composite, in addition to a similar antibacterial activity. The developed ZnO-biochar composite structures, which are more ecological and biocompatible than the ZnO composites derived from graphene sheets, can be applied as electrically conductive and active fillers.

Sensitive Determination of Trace 4-Nitrophenol in Ambient Environment Using a Glassy Carbon Electrode Modified with Formamide-Converted Nitrogen-Doped Carbon Materials.

Sensing trace amounts of 4-nitrophenol (4-NP) as a harmful substance to organisms even in small quantities is of great importance. The present study includes a sensitive and selective electrochemical sensor for detecting 4-NP in natural water samples using formamide-converted nitrogen-carbon materials (shortened to f-NC) as a new material for electrode modification. The structure and morphology of the f-NC were set apart by SEM, TEM, XRD, XPS, FTIR, Raman, and the electrochemical performance of the f-NC were set apart by CV, EIS and CC. We studied the electrochemical behaviour of 4-NP on the glassy carbon electrode modified with f-NC before and after pyrolysis treatment (denoted as f-NC1/GCE and f-NC2/GCE). In 0.2 M of H2SO4 solution, the f-NC2/GCE has an apparent electrocatalytic activity to reduce 4-NP. Under the optimal conditions, the reduction peak current of 4-NP varies linearly, with its concentration in the range of 0.2 to 100 mM, and the detection limit obtained as 0.02 mM (S/N = 3). In addition, the electrochemical sensor has high selectivity, and the stability is quite good. The preparation and application of the sensor to detect 4-NP in water samples produced satisfactory results, which provides a new method for the simple, sensitive and quantitative detection of 4-NP.

Carbon-Based Electrocatalyst Design with Phytic Acid-A Versatile Biomass-Derived Modifier of Functional Materials.

Increasing energy demands exacerbated by energy shortages have highlighted the urgency of research on renewable energy technologies. Carbon materials that can be employed as advanced electrodes and catalysts can increase the accessibility of efficient and economical energy conversion and storage solutions based on electrocatalysis. In particular, carbon materials derived from biomass are promising candidates to replace precious-metal-based catalysts, owing to their low cost, anti-corrosion properties, electrochemical durability, and sustainability. For catalytic applications, the rational design and engineering of functional carbon materials in terms of their structure, morphology, and heteroatom doping are crucial. Phytic acid derived from natural, abundant, and renewable resources represents a versatile carbon precursor and modifier that can be introduced to tune the aforementioned properties. This review discusses synthetic strategies for preparing functional carbon materials using phytic acid and explores the influence of this precursor on the resulting materials' physicochemical characteristics. We also summarize recent strategies that have been applied to improve the oxygen reduction performance of porous carbon materials using phytic acid, thereby offering guidance for the future design of functional, sustainable carbon materials with enhanced catalytic properties.

Designing Hollow Carbon Sphere with Hierarchal Porous for Na-S Systems with Ultra-Long Cycling Stabilities.

Captured by the low-cost and high theoretical specific capacity, Na-S systems have garnered much attention. However, their intermediate products (dissolved polysulfide) are always out of control. Considering the excellent space confinements and conductivity, they have been regarded as promising candidates. Herein, the hollow spheres with suitable thickness shell (~20 nm) are designed as hosting materials, accompanied by in-depth complexing. Benefitting from the abundant micro-pores (mainly about conical-type and slits-type pores < 1.0 nm), the active S4 molecules are successfully filled in the pores through vacuum tube sealing technology, effectively avoiding the process from solid S8 to liquid Na2S6. As cathode for Na-S systems, their capacity could remain at 920 mAh g−1 at 0.1 C after 100 cycles. Even at 10.0 C, the capacity still remained at about 310 mAh g−1 after 7000 cycles. Supported by the detailed kinetic behaviors, the improvement of ions diffusion behaviors is noted, bringing about the effective thorough redox reactions. Moreover, the enhanced surface-controlling behaviors further induces the evolution of rate properties. Therefore, their stable phase changing is further confirmed through in situ resistances. Thus, the work is anticipated to offer significant design for hosting carbon materials and complexing manners.

A Review on Cyanide Gas Elimination Methods and Materials.

Cyanide gas is highly toxic and volatile and is among the most typical toxic and harmful pollutants to human health and the environment found in industrial waste gas. In the military context, cyanide gas has been used as a systemic toxic agent. In this paper, we review cyanide gas elimination methods, focusing on adsorption and catalysis approaches. The research progress on materials capable of affecting cyanide gas adsorption and catalytic degradation is discussed in depth, and the advantages and disadvantages of various materials are summarized. Finally, suggestions are provided for future research directions with respect to cyanide gas elimination materials.