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[Display omitted] Owing to the high cost of precious metal catalysts for the oxygen evolution reaction (OER), the production of highly efficient and affordable electrocatalysts is important for generating pollution-free and renewable energy via electrochemical processes. A facile hydrothermal approach was employed to synthesize hybrid mesoporous iron-nickel bimetallic sulfides @ P, N -doped carbon for the OER. The prepared Fe 0.5 NiS 2 @C exhibited an overpotential (η) of 250 mV at 10 mA/cm2. This exceeded the overpotentials recently reported for surface-modified P, N -doped carbon-based catalysts for the OER in a 1 M KOH medium. Moreover, the Fe 0.5 NiS 2 @C catalyst showed a notable Tafel slope of 90.5 mV/dec with long-dated stability even after 24 h at 10 mA/cm2. The superior OER performance of the Fe 0.5 NiS 2 @C catalysts may be due to their large surface area, sheet-like morphology with abundant active sites, fast transfer of mass and electrons, control of the electronic structure by co-treatment with heteroatoms (e.g., P and N), and the synergistic effect of bimetallic sulfides, making them favorable catalysts for the oxygen evolution reaction. Density functional theory (DFT) calculations showed that the Fe 0.5 NiS 2 @C catalyst exhibited strong H 2 O-adsorption energy. The enhanced OER activity of Fe 0.5 NiS 2 @C was attributed to its higher surface area, favorable H 2 O adsorption energy, improved electron transfer efficiency, and lower Gibbs free energy compared to those of the other proposed catalysts. [ABSTRACT FROM AUTHOR]

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The production of affordable advanced porous materials is necessary for applications involving the capture of CO2. This study aimed to investigate the use of inexpensive liquid precursors in the production of CO2 sorbents. Porous precursors were produced through solvothermal processing of ethylene glycol via dehydration using sulfuric acid. Various pyrolysis and activation techniques were utilized on a carbon precursor to examine how different heat treatment methods affect surface chemical properties and the behavior of static CO2 adsorption at temperatures of 273 K, 298 K, and 313 K. Out of the studied carbons, the urea‐treated pyrolyzed sample exhibited a CO2 uptake capacity of 0.93 mmol g−1 at a pressure of 0.15 bar and a temperature of 298 K. This carbon exhibited a remarkable CO2/N2 selectivity of 46, mainly due to its microporosity and a nitrogen content of 8.3 atomic percent. Moreover, the investigation of adsorption and chemical properties unveiled that nonoxidized sulfur exhibits favorable effects on CO2 adsorption, particularly at the temperature of 298 K. This study provides evidence that liquid precursors can be effectively employed to generate porous doped functional carbons or precursors using solvothermal conditions. [ABSTRACT FROM AUTHOR]

Biomass-derived activated carbon has attracted global attention for supercapacitor applications owing to the limitations of depletable resources and the high cost of conventional activated carbon manufacturing processes. Activated carbon for energy storage requires a large surface area for performing a high energy density, which is the main challenge for biomass-derived activated carbon. Here, we suggest a protein-rich mealworm as a competitive raw material for the activated carbon manufacturing process. Mealworm-based N-doped mesoporous carbon was developed through the synergistic effect of intrinsic amino acids and fatty acids in the mealworm and a KOH activation process. The mealworm-based N-doped mesoporous carbon electrode exhibited a competitive specific capacity at both low and high current densities (154.8 F/g at a current density of 0.2 A/g and 137 F/g at a current density of 5.0 A/g) owing to the high specific surface area (2,470.5 m2/g) and N-doped carbon structure. This superior energy storage capability contributed to its optimized mesoporous morphology and an N-doped carbon structure, which was generated during the KOH activation process. [ABSTRACT FROM AUTHOR]

Continuous accumulation and emission into the atmosphere of anthropogenic carbon dioxide (CO2), a major greenhouse gas, has been recognized as a primary contributor to climate change associated with the global warming and acidification of oceans. This has led to drastic changes in the natural ecosystem, and hence an unhealthy ecological environment for human society. Thus, the effective mitigation of the ever increasing CO2 emission has been recognized as the most important global challenge. To achieve zero carbon footprint, novel materials and approaches are required for potentially reducing the CO2 release, while our current fossil-fuel-based energy must be replaced by renewable energy free from emissions. In this paper, porous carbons with hierarchical pore structures are promising for CO2 adsorption and electrochemical CO2 reduction owing to their high specific surface area, excellent catalytic performance, low cost and long-term stability. Since efficient gas-phased (electro) catalysis involves the access of reactants to active sites at the gas-liquid-solid triple phase, the hierarchical porous carbon materials possess multiple advantages for various CO2-related applications with enhanced volumetric and gravimetric activities (e.g., CO2 uptake and current density) for practical operations. Recent studies have demonstrated that porous carbon materials exhibited notable activities as CO2 adsorbents and provided facile conducting pathways and mass diffusion channels for efficient electrochemical CO2 reduction even under the high current operation conditions. Herein, we summarize recent advances in porous carbon materials for CO2 capture, storage, and electrochemical conversion. Prospectives and challenges on the rational design of porous carbon materials for scalable and practical CO2 capture and conversion are also discussed.v [ABSTRACT FROM AUTHOR]

Continuous accumulation and emission into the atmosphere of anthropogenic carbon dioxide (CO2), a major greenhouse gas, has been recognized as a primary contributor to climate change associated with the global warming and acidification of oceans. This has led to drastic changes in the natural ecosystem, and hence an unhealthy ecological environment for human society. Thus, the effective mitigation of the ever increasing CO2 emission has been recognized as the most important global challenge. To achieve zero carbon footprint, novel materials and approaches are required for potentially reducing the CO2 release, while our current fossil-fuel-based energy must be replaced by renewable energy free from emissions. In this paper, porous carbons with hierarchical pore structures are promising for CO2 adsorption and electrochemical CO2 reduction owing to their high specific surface area, excellent catalytic performance, low cost and long-term stability. Since efficient gas-phased (electro)catalysis involves the access of reactants to active sites at the gas-liquid-solid triple phase, the hierarchical porous carbon materials possess multiple advantages for various CO2-related applications with enhanced volumetric and gravimetric activities (e.g., CO2 uptake and current density) for practical operations. Recent studies have demonstrated that porous carbon materials exhibited notable activities as CO2 adsorbents and provided facile conducting pathways and mass diffusion channels for efficient electrochemical CO2 reduction even under the high current operation conditions. Herein, we summarize recent advances in porous carbon materials for CO2 capture, storage, and electrochemical conversion. Prospectives and challenges on the rational design of porous carbon materials for scalable and practical CO2 capture and conversion are also discussed.

N, P dual‐doped watermelon peel‐derived carbon (NPW) was prepared and found to exhibit a larger specific surface area of 1809 m2 g−1 and improved hierarchically interconnected pores than N‐doped and P‐doped carbons. The NPW electrode exhibits excellent electrochemical activity in a three‐electrode setup with 1 M H2SO4, 6 M KOH, and 1 M Na2SO4 electrolytes; with high specific capacitance (498.8, 397.6, and 378.6 F g−1 at 1 A g−1, respectively) and an average capacitance retention of ∼96.9 % after 10,000 charge‐discharge cycles at 10 A g−1. The NPW//NPW‐based symmetric cell with 1 M H2SO4‐PVA‐electrolyte provided a high energy density of 71.84 Wh kg−1 at 1 A g−1 and a specific capacitance of 263.9 F g−1. In the neutral electrolyte, NPW showed a wider operating voltage window of up to 2.0 V with no discernible anodic current and delivered 97.11 Wh kg−1 energy density. [ABSTRACT FROM AUTHOR]

N/S-co-coped carbon nanoparticles (mean size ∼ 80–90 nm) have been synthesized by a simple strategy based on the preparation of polypyrrole nanospheres by a room temperature oxidative polymerization process followed by their S doping using elemental sulfur. The developed materials combine a highly disordered microstructure with a high level of N- and S-doping and short solid-state diffusion distances. These characteristics endow the materials with a large number of readily accessible adsorption/insertion sites for sodium storage, yielding thus high reversible capacities (of up to 726 mAh g−1 at 0.1 A g−1) that are well retained at high current rates (up to 188 mAh g−1 at 10 A g−1). The material with optimized Na storage performance was tested as the negative electrode in a sodium-ion capacitor, using as the positive electrode highly porous nanoparticles prepared by KHCO 3 activation of the same polypyrrole nanospheres (S BET ∼ 2970 m2 g−1). The sodium-ion capacitor with an optimized positive-to-negative electrode mass ratio of 2 delivers as much as 69 Wh kg−1 at a high-power density of 25 kW kg−1, and can be successfully charged and discharged for 10000 cycles experiencing a capacity loss of only 0.0024% per cycle at 2 A g−1. [Display omitted] • N/S-co-coped carbon nanoparticles were synthesized from polypyrrole and sulfur. • They combine disordered structure, high S/N-doping and short diffusion distances. • The materials achieve high capacity and rate performance below 1.5 V vs. Na+/Na. • Full NIC was built using highly porous PPy-derived nanoparticles as the cathode. • The NIC achieved high energy density and showed high cycling stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Covalent organic framework-derived carbon was reviewed for the first time. • Carbon from porous organic- or covalent organic-polymers was also analyzed. • Application of derived carbon in adsorption and catalysis was reviewed. • Future perspectives were also given to readers in the relevant fields. Recent advancements in porous materials have significantly impacted energy storage/conversion and environmental remediation. Covalent organic framework (COF)-derived carbons (CDCs) have recently attracted significant scientific attention. COFs, formed by the ordered arrangement of organic linkers, create atomically precise porous frameworks but lose crystallinity upon high-temperature pyrolysis, resulting in mostly amorphous carbonaceous materials with high defect sites. Non-crystalline precursors, e.g. porous organic polymers (POPs) or covalent organic polymers (COPs), yield carbonaceous materials similar to CDCs. These materials can be synthesized using linkers similar to those in COFs. This review focuses on the preparation and applications of CDC materials in adsorption and catalysis, including those derived from POPs and COPs, while excluding those from conventional non-porous polymers. Future perspectives, together with the summary of the review, are also given to readers in the relevant fields. [ABSTRACT FROM AUTHOR]

Aldehydes are essential chemicals for industrial feedstock. However, the traditional processes to produce these chemicals face many limitations, such as waste generation, low selectivity, or high cost. Herein, we report the synthesis and characterization of a group of porous heteroatom (P, B or N)‐doped carbons and their use as catalysts for the oxidation of primary alcohols by activating peroxydisulfate. Among the heteroatom‐doped carbons, porous N‐doped carbons pyrolyzed at 700 or 800 °C show the highest activity. Experimental studies were performed suggesting a considerable contribution of a non‐radical oxidation process. Furthermore, N‐doped carbons can act as a catalyst in the oxidation of a large substrate scope of substituted alcohols. [ABSTRACT FROM AUTHOR]

Fuel cells are a promising alternative to non-renewable energy production industries such as petroleum and natural gas. The cathodic oxygen reduction reaction (ORR), which makes fuel cell technology possible, is sluggish under normal conditions. Thus, catalysts must be used to allow fuel cells to operate efficiently. Traditionally, platinum (Pt) catalysts are often utilized as they exhibit a highly efficient ORR with low overpotential values. However, Pt is an expensive and precious metal, posing economic problems for commercialization. Herein, advances in carbon-based catalysts are reviewed for their application in ORRs due to their abundance and low-cost syntheses. Various synthetic methods from different renewable sources are presented, and their catalytic properties are compared. Likewise, the effects of heteroatom and non-precious metal doping, surface area, and porosity on their performance are investigated. Carbon-based support materials are discussed in relation to their physical properties and the subsequent effect on Pt ORR performance. Lastly, advances in fuel cell electrolytes for various fuel cell types are presented. This review aims to provide valuable insight into current challenges in fuel cell performance and how they can be overcome using carbon-based materials and next generation electrolytes.

Abstract Global access to sanitary water is of utmost importance to human health. Presently, textile dye water pollution and cigarette pollution are both plaguing the environment. Herein, waste cigarette filters (CFs) are converted into useful carbon-based adsorbent materials via a facile, microwave-assisted carbonization procedure. The CFs are activated and co-doped with phosphorus and nitrogen simultaneously to enhance their surface characteristics and adsorbent capability by introducing chemisorptive binding sites to the surface. The doped carbonized CF (DCCF) and undoped carbonized CF (CCF) adsorbents are characterized physically to examine their surface area, elemental composition, and surface charge properties. The maximum adsorption capacity of synthesized adsorbents was determined via batch adsorption experiments and Langmuir modelling. Additionally, the influence of different parameters on the adsorption process was studied by varying the adsorption conditions such as adsorbent dosage, initial concentration, contact time, temperature, and pH. The DCCF adsorbent showed a maximum adsorption capacity of 303 mg g− 1. Adsorption of both adsorbents fit best to Langmuir model and pseudo-second order kinetics, indicating chemisorptive mechanism. Both adsorbents showed endothermic adsorption process which is indicated by increasing adsorption capacity with increased temperatures. DCCF exhibited greater adsorption capability than CCF at all temperatures from 25 to 55 °C. The pH of the solution significantly affected the adsorption capacity of CCF while DCCF adsorption is favorable at a wide pH range due to low value of the adsorbent’s point of zero charge. Reusability results showed that both adsorbents can be used over several cycles for removal of dye. Thus, results conclude that the waste DCCF-based adsorbent does not only show a profound potential as a sustainable solution to combat textile dye water pollution but also addresses the valuable use of the CF pollution simultaneously. This approach, which can target two major pollutants, is attractive due to its ease of preparation, negligible cost, and versatility in application.

Heteroatom-doped carbon can significantly improve the electrochemical performance of LiFePO4 cathodes, but it is limited by the complex preparation process and expensive dopants. A self-assembled S-doped LiFePO4@N/S-doped C coreâ€"shell structured composites were synthesized by a convenient solvothermal method are reported. The structure and the electrochemical performance of the composites were characterized. In the S-doped LiFePO4@N/S-doped C composites, the glucose-derived carbon microspheres were attached by LiFePO4/C particles to form secondary particles in the coreâ€"shell structure. The thioacetamide regulated the morphology of LiFePO4/C particles and provided N and S atoms to dope the composites. The S-doped LiFePO4@N/S-doped C composites delivered specific discharge capacities of 157.81 mAh gâˆ'1 at 0.1 C and 121.26 mAh gâˆ'1 at 5 C, and capacity retention of 99.88% after 100 charge/discharge cycles. The excellent electrochemical performance of the S-doped LiFePO4@N/S-doped C composites can be attributed to the synergism of thioacetamide and glucose. [ABSTRACT FROM AUTHOR]

Recently, electro-oxidation of kraft lignin has been reported as a prominent electrochemical reaction to generate hydrogen at lower overpotential in alkaline water electrolysis. However, this reaction is highly limited by the low performance of existing electrocatalysts. Herein, we report a novel yet effective catalyst that comprises nonprecious trimetallic (Ni, Fe, and Co) nanoalloy as a core in a phosphidated nitrogen-doped carbon shell (referred to as sample P-NiFeCo/NC) for efficient electro-oxidation of kraft lignin at different temperatures in alkaline medium. The as-synthesized catalyst electro-oxidizes lignin only at 0.2 V versus Hg/HgO, which is almost three times less positive potential than in the conventional oxygen evolution reaction (0.59 V versus Hg/HgO) at 6.4 mA/cm2 in 1 M KOH. The catalyst demonstrates a turnover frequency (TOF) three to five times greater in lignin containing 1 M KOH than that of pure 1 M KOH. More importantly, the catalyst P-NiFeCo/NC shows theoretical hydrogen production of about 0.37 μmoles/min in the presence of lignin, much higher than that in pure 1 M KOH (0.0078 μ moles/min). Thus, this work verifies the benefit of the NiFeCo nanoalloy incorporated in carbon matrix, providing the way to realize a highly active catalyst for the electro-oxidation of kraft lignin. [ABSTRACT FROM AUTHOR]

The continual rise of the CO2 concentration in the Earth's atmosphere is the foremost reason for environmental concerns such as global warming, ocean acidification, rising sea levels, and the extinction of various species. The electrochemical CO2 reduction (CO2RR) is a promising green and efficient approach for converting CO2 to high-value-added products such as alcohols, acids, and chemicals. Developing efficient and low-cost electrocatalysts is the main barrier to scaling up CO2RR for large-scale applications. Heteroatom-doped porous carbon-based (HA-PCs) catalysts are deemed as green, efficient, low-cost, and durable electrocatalysts for the CO2RR due to their great physiochemical and catalytic merits (i.e., great surface area, electrical conductivity, rich electrical density, active sites, inferior H2 evolution activity, tailorable structures, and chemical–physical–thermal stability). They are also easily synthesized in a high yield from inexpensive and earth-abundant resources that meet sustainability and large-scale requirements. This review emphasizes the rational synthesis of HA-PCs for the CO2RR rooting from the engineering methods of HA-PCs to the effect of mono, binary, and ternary dopants (i.e., N, S, F, or B) on the CO2RR activity and durability. The effect of CO2 on the environment and human health, in addition to the recent advances in CO2RR fundamental pathways and mechanisms, are also discussed. Finally, the evolving challenges and future perspectives on the development of heteroatom-doped porous carbon-based nanocatalysts for the CO2RR are underlined. [ABSTRACT FROM AUTHOR]

There is a growing need to develop sustainable electrocatalysts to facilitate the reduction of molecular oxygen that occurs at the cathode in fuel cells, due to the excessive cost and limited availability of precious metal-based catalysts. This study reports the synthesis and characterization of phosphorus and nitrogen co-doped carbon (PNDC) and silicon, phosphorus, and nitrogen tri-doped carbon (SiPNDC) electrocatalysts derived from molasses. This robust microwave-assisted synthesis approach is used to develop a low cost and environmentally friendly carbon with high surface area for application in fuel cells. Co-doped PNDC as well as tri-doped SiPNDC showed Brunauer–Emmet–Teller (BET) surface areas of 437 and 426 m2 g−1, respectively, with well-developed porosity. However, examination of X-ray photoelectron spectroscopy (XPS) data revealed significant alteration in the doping elemental composition among both samples. The results obtained using rotating disk electrode (RDE) measurements show that tri-doped SiPNDC achieves much closer to a 4-electron process than co-doped PNDC. Detailed analysis of experimental results acquired from rotating ring disk electrode (RRDE) studies indicates that there is a negligible amount of peroxide formation during ORR, further confirming the direct-electron transfer pathway results obtained from RDE. Furthermore, SiPNDC shows stable oxygen reduction reaction (ORR) performance over 2500 cycles, making this material a promising electrocatalyst for fuel cell applications.

• Novel Fe-CoS 2 @NC with elevated specific area and pore size are designed and fabricated. • Electrosorption of Yb(III) by Fe-CoS 2 @NC and Fe-CoS 2 is comparatively studied. • Electrosorption mechanism mainly depends on electric double layers and pseudo-capacitance. • Fe-CoS 2 @NC is successfully recycled for successive 5 times with less than 2% degradation. In this study, the novel Fe-doped CoS 2 @nitrogen-doped carbon (Fe-CoS 2 @NC) composites were manufactured and investigated as the capacitive deionization (CDI) electrode materials for electrosorption of Yb(III). The as-prepared materials were characterized with X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, N 2 adsorption–desorption test with Brunauer-Emmett-Teller method, Raman spectroscopy, and X-ray photoelectron spectroscopy. The electrochemical tests, including cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy, revealed that Fe-CoS 2 @NC exhibited the better electrochemical performance with a specific capacitance of 58.41 F g−1 than Fe-CoS 2 @0.5NC and Fe-CoS 2. The electrosorption results demonstrated that Fe-CoS 2 @NC possessed the Yb(III) uptake of 129.4 mg·g−1 within 60 min at a voltage of 1.2 V and a flow rate of 20 mL·min−1. After five successive sorption–desorption cycles, the electrosorption efficiency of Fe-CoS 2 @NC remained at 98 %, exhibiting the robust durability for future industrial application. Furthermore, Fe-CoS 2 @NC also showed the favorable electrosorption performance towards various rare earth ions, especially for heavy rare earth ions. The mechanism analysis indicated that the impressive electrosorption performance is attributed to the synergistic contribution by the electric double layers of carbonaceous matrix and the pseudo-capacitance that induced by the redox reactions of Fe atom. [ABSTRACT FROM AUTHOR]

[Display omitted] Nitrogen- and transition metal-dual doped carbon materials with low cost and high catalytic performances are considered as one of promising alternatives for noble metal catalysts in acceleration of oxygen reduction reaction (ORR). In this work, three-dimensional (3D) self-supporting superstructures of iron carbide (Fe 3 C) nanoclusters entrapped in manganese (Mn)- and nitrogen (N)-dual doped carbon nanosheets covered with double-sided nanoneedles carbon arrays (Fe 3 C/Mn,N-NCAs) are simply synthesized by a coordination pyrolysis method, in which dicyandiamide mainly behaves as nitrogen source and 1-(2-pyridylazo)-2-naphthol (PAN) as carbon source. Integration of the unique 3D self-supporting superstructures and synergistic effects of the multi-compositions, the as-obtained catalyst displays appealing ORR performance such as the much positive onset potential (E onset = 0.98 V vs. RHE) and half-wave potential (E 1/2 = 0.88 V vs. RHE), as well as a just 10 mV negative shift in E 1/2 after 2000 cycles, surpassing commercial Pt/C. This work provides some valuable perspectives for preparation of high-efficiency and low-cost non-noble metal ORR electrocatalysts in energy transformation and storage correlated systems. [ABSTRACT FROM AUTHOR]

Fuel cells are a promising alternative to non-renewable energy production industries such as petroleum and natural gas. The cathodic oxygen reduction reaction (ORR), which makes fuel cell technology possible, is sluggish under normal conditions. Thus, catalysts must be used to allow fuel cells to operate efficiently. Traditionally, platinum (Pt) catalysts are often utilized as they exhibit a highly efficient ORR with low overpotential values. However, Pt is an expensive and precious metal, posing economic problems for commercialization. Herein, advances in carbon-based catalysts are reviewed for their application in ORRs due to their abundance and low-cost syntheses. Various synthetic methods from different renewable sources are presented, and their catalytic properties are compared. Likewise, the effects of heteroatom and non-precious metal doping, surface area, and porosity on their performance are investigated. Carbon-based support materials are discussed in relation to their physical properties and the subsequent effect on Pt ORR performance. Lastly, advances in fuel cell electrolytes for various fuel cell types are presented. This review aims to provide valuable insight into current challenges in fuel cell performance and how they can be overcome using carbon-based materials and next generation electrolytes. [ABSTRACT FROM AUTHOR]

Herein, a facile synthesis of heteroatom doped biochar is reported. The material is characterized and analyzed in detail for its application as a low-cost adsorbent for removal of a toxic dye pollutant, Methylene Blue (MB), from aqueous solution. Synthesized material showed enhanced surface area compared to parent biochar (458 to802 m2g−1) The adsorbent's performance is investigated using batch adsorption methods with experiments conducted at varying conditions of adsorbent dosage, initial dye concentration (50–500 mg/L), and pH (3–11). Adsorption of MB onto two different adsorbents such as biochar (BC) and doped BC, is fitted using Langmuir and Freundlich isotherms with the experimental data correlating most accurately with Langmuir modelling, indicating chemisorption mechanism of dye onto adsorbent. Maximum monolayer equilibrium adsorption from Langmuir equation is found to be 129.8 and 357.1 mg/g for pure BC and Phosphorus and Nitrogen co-doped BC (PNBC), respectively. Pseudo-first and -second order kinetic models are applied to investigate the adsorption mechanism of PNBC. Adsorption mechanism followed pseudo-second order model well, with correlation coefficients very close to 1. The results indicate that microwave-assisted heteroatom co-doped BC showed superior performance as adsorbent for the adsorption of MB dye from aqueous solution. [ABSTRACT FROM AUTHOR]

Global access to sanitary water is of utmost importance to human health. Presently, textile dye water pollution and cigarette pollution are both plaguing the environment. Herein, waste cigarette filters (CFs) are converted into useful carbon-based adsorbent materials via a facile, microwave-assisted carbonization procedure. The CFs are activated and co-doped with phosphorus and nitrogen simultaneously to enhance their surface characteristics and adsorbent capability by introducing chemisorptive binding sites to the surface. The doped carbonized CF (DCCF) and undoped carbonized CF (CCF) adsorbents are characterized physically to examine their surface area, elemental composition, and surface charge properties. The maximum adsorption capacity of synthesized adsorbents was determined via batch adsorption experiments and Langmuir modelling. Additionally, the influence of different parameters on the adsorption process was studied by varying the adsorption conditions such as adsorbent dosage, initial concentration, contact time, temperature, and pH. The DCCF adsorbent showed a maximum adsorption capacity of 303 mg g− 1. Adsorption of both adsorbents fit best to Langmuir model and pseudo-second order kinetics, indicating chemisorptive mechanism. Both adsorbents showed endothermic adsorption process which is indicated by increasing adsorption capacity with increased temperatures. DCCF exhibited greater adsorption capability than CCF at all temperatures from 25 to 55 °C. The pH of the solution significantly affected the adsorption capacity of CCF while DCCF adsorption is favorable at a wide pH range due to low value of the adsorbent's point of zero charge. Reusability results showed that both adsorbents can be used over several cycles for removal of dye. Thus, results conclude that the waste DCCF-based adsorbent does not only show a profound potential as a sustainable solution to combat textile dye water pollution but also addresses the valuable use of the CF pollution simultaneously. This approach, which can target two major pollutants, is attractive due to its ease of preparation, negligible cost, and versatility in application. [ABSTRACT FROM AUTHOR]

The continual rise of the CO2 concentration in the Earth’s atmosphere is the foremost reason for environmental concerns such as global warming, ocean acidification, rising sea levels, and the extinction of various species. The electrochemical CO2 reduction (CO2RR) is a promising green and efficient approach for converting CO2 to high-value-added products such as alcohols, acids, and chemicals. Developing efficient and low-cost electrocatalysts is the main barrier to scaling up CO2RR for large-scale applications. Heteroatom-doped porous carbon-based (HA-PCs) catalysts are deemed as green, efficient, low-cost, and durable electrocatalysts for the CO2RR due to their great physiochemical and catalytic merits (i.e., great surface area, electrical conductivity, rich electrical density, active sites, inferior H2 evolution activity, tailorable structures, and chemical–physical–thermal stability). They are also easily synthesized in a high yield from inexpensive and earth-abundant resources that meet sustainability and large-scale requirements. This review emphasizes the rational synthesis of HA-PCs for the CO2RR rooting from the engineering methods of HA-PCs to the effect of mono, binary, and ternary dopants (i.e., N, S, F, or B) on the CO2RR activity and durability. The effect of CO2 on the environment and human health, in addition to the recent advances in CO2RR fundamental pathways and mechanisms, are also discussed. Finally, the evolving challenges and future perspectives on the development of heteroatom-doped porous carbon-based nanocatalysts for the CO2RR are underlined.

Biomass‐derived carbon aerogels refer to carbon aerogels prepared using biomass as the precursor. They are environmentally friendly, cheap and have abundant precursors, which have aroused widespread interest and exhibit excellent performance in the fields of electrocatalysis (e. g. for the hydrogen evolution, oxygen evolution and oxygen reduction reactions) and energy storage (i. e. as electrode materials for supercapacitors). Furthermore, metal species can be incorporated into the porous carbon matrix without destroying the original 3D structure whilst improving its conductivity and electrochemical performance. Above all, most biomass materials contain nitrogen functionalities, and can be doped in situ (self‐doping) with heteroatoms, such as N, without any additives, thereby creating additional defects and active centers with augmented electron density and electron‐contributing attributes. Herein, the electrochemical applications of biomass‐derived carbon aerogels reported during the last decade, especially in the field of water electrolysis, metal‐air batteries, fuel cells and supercapacitors, are summarized. Current research challenges and future directions are briefly highlighted. [ABSTRACT FROM AUTHOR]

Ni,N‐doped carbon catalysts have shown promising catalytic performance for CO2 electroreduction (CO2R) to CO; this activity has often been attributed to the presence of nitrogen‐coordinated, single Ni atom active sites. However, experimentally confirming Ni−N bonding and correlating CO2 reduction (CO2R) activity to these species has remained a fundamental challenge. We synthesized polyacrylonitrile‐derived Ni,N‐doped carbon electrocatalysts (Ni‐PACN) with a range of pyrolysis temperatures and Ni loadings and correlated their electrochemical activity with extensive physiochemical characterization to rigorously address the origin of activity in these materials. We found that the CO2R to CO partial current density increased with increased Ni content before plateauing at 2 wt % which suggests a dispersed Ni active site. These dispersed active sites were investigated by hard and soft X‐ray spectroscopy, which revealed that pyrrolic nitrogen ligands selectively bind Ni atoms in a distorted square‐planar geometry that strongly resembles the active sites of molecular metal–porphyrin catalysts. [ABSTRACT FROM AUTHOR]

High-performance bifunctional electrocatalysts based on nickel/nickel oxide nanoparticles and nitrogen-doped activated carbon, derived from biomass waste (cauliflower leaves) were synthesized by a facile one-step process. The Ni and NiO compositions were controlled by varying the temperature during pyrolysis, which had significant effects on the crystallographic structure of the resulting hybrid and electrocatalytic properties. The Ni/NiO/N-doped activated carbon obtained at 500 °C shows modest Tafel slopes of 70 and 121 mV dec−1 along with overpotentials of 346 and 180 mV to drive a current density of 10 mA cm−2 for oxygen evolution and hydrogen evolution reactions in 0.1 M KOH electrolyte. In a two-electrode electrolyser the hybrid bifunctional electrocatalyst requires only 1.688 V to reach 10 mA cm−2 current density, confirming excellent rate capability and robust stability with variable current densities of 10–30 mA cm−2. The electrocatalytic performance of the NiO x -AC-500 || NiO x -AC-500 cell is comparable to that of recently reported electrolysers. The superior electrocatalytic performance of our electrocatalyst is due to synergies between Ni and NiO in a hierarchically porous N-doped carbon structure, rich in active sites and efficient charge transfer. This work offers a sustainable approach to develop eco-friendly bifunctional electrocatalysts for high-performance water splitting. Image 1 • Ni/NiO conjugated with N-doped activated carbon from waste cauliflower leaf by 1-step pyrolysis. • Ni/NiO nanoparticle and N-doped carbon synergy offers efficient active sites and charge transfer. • High performing bifunctional electrocatalyst for OER and HER in alkaline media. • Excellent anode/cathode rate capability and stability in electrolyser for water splitting. [ABSTRACT FROM AUTHOR]

The performance of the oxygen reduction reaction (ORR) is a core issue in of fuel cells. ORR is a slow kinetic process; platinum normally is used to accelerate the reaction. This is a bottleneck for further development of fuel cells. Transition metal and heteroatom co-doped carbon materials have great potential in ORR catalysis. However, one-step synthesis of high activity and stability transition metal and heteroatom co-doped electrocatalysts is still a challenge. In this work, nitrogen, fluorine, and cobalt co-doped carbon catalyst, MPCo-950-5, is prepared from melamine, polytetrafluoroethylene, and cobalt acetate by a one-step method. MPCo-950-5 with a graphene-like structure and its specific surface area is 642 m2g-1. The ORR half-wave potential of MPCo-950-5 is positively shifted by 35 mV compared to that of commercial Pt/C. In addition, MPCo-950-5 also shows excellent stability and methanol tolerance. This work serves as a simple and feasible method for preparing high ORR active transition metal and heteroatom co-doped carbon materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Natural bio-sourced polymers are sustainable precursors for doped carbon materials. • Role of functionalities of natural bio-sourced polymers for the synthesis of SACs. • Techniques for visualization and determination of coordination atmosphere of SACs. • A general approach for the synthesis of SACs via pyrolysis and their applications. Natural bio-sourced polymers have been utilized as potential support materials and sustainable source for the preparation of doped carbon materials via high temperature heat treatment due to the presence of heteroatoms (N-, O-, P- and S) in the form of various functional groups. Moreover, free availability of these functional groups facilitates the incorporation and binding of metal ions through complexation process that is believed to be essential for the synthesis of immobilized catalysts and single atom catalysts (SACs). SACs are the key chain between homogenous and heterogeneous catalysts due to their unprecedented robustness in terms of catalytic activity and stability. Natural bio-sourced polymers have emerged as one of the irreplaceable substitutes to synthesize SACs by providing anchoring sites to the metal ions and their subsequent transformation into a carbonaceous material generating isolated metal atomic sites. The type of coordination atmosphere of single metal atom enriches catalytic activity by establishing noble interactions with the support material. The primary aim of this review article is to discuss the advancement and provide insight about the utilization of various natural bio-sourced polymers in the preparation of different metal-based SACs. Moreover, we have discussed individual steps for the synthesis of SACs and techniques required for the visualization and determining the coordination environment of single atom sites. At the end, challenges and future prospective on natural bio-sourced polymer-based SACs synthesis and other applications are deliberated. [ABSTRACT FROM AUTHOR]

Zeolite template carbon (ZTC) is a carbon material composed of a three-dimensional network of graphene nanoribbons (GNR), and thus, is expected to exhibit electronic characteristics identical to those of GNR. ZTC is capable of doping heteroatoms in its structure, which offers the advantage of controlling its electronic properties by the presence of the heteroatoms. In this study, we prepared heteroatom-doped ZTCs and applied them to an ion-sensitive field effect transistor (ISFET), for investigating the effect of heteroatom doping on its electronic properties. The ISFET characteristics of un-doped ZTC include bipolarity, whereas oxygen-doped ZTC shows p-type semiconductor characteristics, and nitrogen-doped ZTC shows n-type characteristics. Furthermore, copper and nitrogen co-doped ZTC exhibits high sensor sensitivity (the change of electric conductivity reaches up to 50%) as a carbon-based ISFET. As a result of the analytical evaluation, a copper-nitrogen complex is formed in the co-doped ZTC, and the electronic interaction between copper and nitrogen atoms is able to change electrochemically. Owing to the presence of the copper-nitrogen complex, the co-doped ZTC shows specific ISFET characteristics.

SiO2 is regarded as one of the most promising anode materials for Li‐ion batteries due to its high capacity, low cost and other merits. However, the poor conductivity and the volume change are still hindering its practical applications. In this work, a rambutan‐inspired structure is designed to fabricate amorphous SiO2@N, P co‐doped porous carbon frameworks from biomass. The carbon shell could connect with each other, providing good conductivity. After partially etching of the SiO2, the yolk‐shell structure could buffer the volume changes of SiO2 during the charge/discharge processes without destroying the conducting shell. Besides, N, P doping and graphite nano crystallites in the frameworks could also offer more active sites for Li+ storage. As a result, the composite can not only exhibit excellent rate performance nearly 300 mAh g−1 at a current density of 2000 mA g−1, but also deliver a surprisingly stable reversible capacity of 373 mAh g−1 over 1000 cycles at the current density of 500 mA g−1 with the Coulombic efficiency beyond 99%. Considering the facile preparation and satisfactory lithium storage abilities, this composite design could be able to extend for practical battery application. [ABSTRACT FROM AUTHOR]

Considering the lack of lithium resources, sodium- and potassium-ion storage systems possess great potential for large scale energy storage. However, the slow charge storage kinetics of graphite hinders the intercalation of large sodium and potassium ions, leading to low capacity and poor cycling stability. Herein, we report a nitrogen-doped carbon nanotube coated porous carbon derived from the metal-organic framework precursor for boosting the sodium and potassium ion storage. The carbon product tested as anode deliverers a high specific capacity of 320/339 mAh g−1 at 0.05 A g−1 in sodium/potassium ion batteries. Ex-situ X-ray diffraction studies indicate that the dominant charge storage mechanism in the carbon is based on adsorption, rather than intercalation. In addition, kinetics analysis further confirms that the capacitive-controlled capacity is dominant in the carbon electrode. To further illustrate the merits of metal-organic framework derived nanoporous materials, hybrid sodium and potassium ion capacitors are assembled by using the carbon anode and cathode both from metal organic frameworks. A high energy density of 118/126 W h kg−1 can be achieved for sodium/potassium ion capacitors. The present work provides a new strategy to design nanostructured carbons for high-performance metal-ion capacitors based on earth-abundant metals besides lithium. • A core (porous carbon)-shell (carbon nanotube) carbon structure is designed. • Adsorption-dominated capacity is revealed by ex-situ XRD and kinetic analysis. • High-performance sodium-/potassium-ion capacitor is fabricated. [ABSTRACT FROM AUTHOR]

High performance electrocatalysts based on nickel nanoparticles and biomass derived carbon were fabricated via a sustainable, inexpensive synthetic route utilizing waste carrot as a naturally occurring carbon precursor containing abundant amounts of phosphorus and oxygen. The electrocatalytic performance of the fabricated electrodes with variable nickel mass loadings (0 ̶ 30 wt %) was investigated. For Ni mass loading of 19.3 wt%, the resulting Ni/P-doped carbon exhibits optimum catalytic activity for oxygen reduction (ORR), oxygen evolution (OER) and hydrogen evolution reaction (HER). The electrocatalyst reveals onset and half-wave potentials of 0.81 and 0.67 V vs. reversible hydrogen electrode (RHE), and a kinetic limiting current density of 13.66 mA cm−2 at 0.1 V vs. RHE for ORR. The material exhibits modest Tafel slopes of 67.6 and 134.9 mV dec−1 and overpotentials of 368 and 297 mV to reach a current density of 10 mA cm−2 for OER and HER, respectively. The results on the composite physicochemical characteristics, electrochemically active surface area, ionic conductivity and ionic diffusivity reveal a sustainable process to fabricate eco-friendly, trifunctional electrocatalysts having high efficiency. Image 1 • Carbon nanomaterial via green low-cost method from waste biomass. • Ni- and P-doped carbon composites via facile one-step pyrolysis. • High performance multifunctional electrocatalyst for ORR, OER and HER. • Large surface area, mesoporous structure, synergistic effect for enhanced performance. • Excellent electron transfer resistance, ionic diffusivity and active surface area. [ABSTRACT FROM AUTHOR]

A new kind of metal‐free, porous, and N,P co‐doped carbon catalyst was prepared from a high crystalline and two dimensional (2D) covalent organic framework (COF). Remarkably, this N,P co‐doped catalyst exhibits an excellent tolerance towards methanol crossover, as well as a comparable oxygen reduction reaction performance to commercial Pt/C. [ABSTRACT FROM AUTHOR]

Heteroatom doped carbon based hierarchical nanostructures are one of most interesting electrode materials for boosting oxygen reduction reaction (ORR) owing to the active electronic structure and appealing structural stability. Herein we demonstrated a 'polymerization-dissolution' method to prepare a highly stable Fe, N, S tri-heteroatom doped core-shell carbon (HCSC) nanostructural ORR catalyst. The unique advantages, including the uniformly dispersed N, S and Fe–N active sites, and the special leaf-like core-shell nanostructure, endow the optimized HCSC catalyst (HCSC-IV-H) owning high-efficient ORR activity. Moreover, a Zn–air battery assembled with HCSC-IV-H exhibits a higher open potential (1.430 V) and lower discharge overpotential, comparing with the commercial IrO 2 + 20% Pt/C catalyst. The present work highlights a novel strategy to construct highly efficient heteroatom doped nano-carbon materials for renewable energy storage and conversion devices. A 'polymerization-dissolution' method that regulates the balance between aniline polymerization and iron metal–organic framework dissolution is provided to prepare different kinds of Fe, N and S co-doped carbon core-shell composites. The optimized hybrid electrocatalysts show excellent ORR catalytic activity and high performance for Zn-air batteries. The detailed analysis on such kinds of catalysts reveals that the uniformly dispersed Fe–N sites, synergistic effect of N and S, and special leaf-like core-shell nanostructure are essential to the excellent ORR activities. Image 1 [ABSTRACT FROM AUTHOR]

Abstract Energy storage based on sodium ions is considered to be one of the most promising candidates for large-scale applications. However, designing nanostructured anodes with ultralong cycle life, superior rate capability, and high specific capacitance is still a challenge. Herein, we report that nitrogen functionalized carbon nanocages with optimized structures as anodes in sodium-ion half cells demonstrate a superior capacity of 402 mA h g−1 at 50 mA g−1, excellent rate performance with 101 mA h g−1 at 10 A g−1, and an ultra-long cycle life by retaining 81% of its initial capacity after 5000 cycles at 10 A g−1. It can be observed that carbons with high nitrogen doping level and few-layer graphene domains are proved to be effective for sodium ion storage. Benefiting from the merits of structure and electrochemical performance of nitrogen functionalized carbon nanocages, the sodium-ion capacitors by using identical carbon electrodes achieves a high energy density of 102.5 W h kg−1 and an outstanding cycle life of 100,000 cycles with 74.2% of the capacity retention. This work opens a new opportunity for designing high-performance carbon electrodes with scalable production for next-generation energy storage. Graphical abstract Image 1 Highlights • Na+ storage is boosted by tuning microstructure, porosity, and doping in carbons. • The as-built all carbon sodium-ion capacitors show high energy and long cycle life. • The facile one-step synthesis approach is promising for advanced energy storage. [ABSTRACT FROM AUTHOR]

The suitable structural design of carbon catalysts is a straightforward strategy to achieve a superior electrocatalytic activity for the oxygen reduction reaction. Herein, we firstly design a three‐dimensional sphere‐and‐flake‐structured Cu, N co‐doped carbon catalyst, via a template‐free method, for robust oxygen reduction reaction. The nanostructure is composed of graphene‐like nanosheets and carbon nanospheres with abundant mesopores, which can expose numerous active sites. Cu2+ and the copolymer of PANI and Cu2+ and melamine play important roles in the construction of the sphere‐and‐flake structure. By optimizing the addition of melamine, the structure of the catalyst can be successfully controlled. The as‐constructed GCNS10 material possesses a large amount of Cu‐Nx sites and exhibits an excellent electrocatalytic activity for the oxygen reduction reaction, delivering a limiting current density (6.14 mA cm−2 at −0.1 V) and stability superior to those of commercial Pt/C materials in 0.1 M KOH solution. These satisfactory performances suggest that GCNS10 is promising as a next‐generation non‐noble‐metal oxygen reduction reaction catalyst. Besides, using an air cathode with the GCNS10 catalyst works well in a Zn‐air battery, indicating that GCNS10 can be used in such devices. A carbon material with 3D sphere‐and‐flake structure is rationally designed for the electroreduction of oxygen. Highly electroactive Cu‐Nx sites are anchored on the catalyst due to the copolymerization of aniline, melamine, and cupric ion. The as‐fabricated GCNS10 catalyst exhibits a remarkable performance towards the oxygen reduction reaction and can be used in Zn‐air batteries. [ABSTRACT FROM AUTHOR]

Abstract Exploring of efficient electrocatalysts based on nonprecious metals is of great importance for the development of hydrogen energy and related energy conversion technologies. Metallic Ni 3 Fe nanoarray is firstly fabricated on carbon cloth as efficient oxygen evolution electrocatalyst. Co, N-dual doped carbon shell derived from metal organic framework is coated on the Ni 3 Fe nanoarray to enhance electrocatalytic activity and stability. The as-prepared composite catalyst only needs a low overpotential of 170 mV to drive 10 mA cm−2 current density in alkaline solution, and an overpotential of 370 mV in carbonate buffer solution. Moreover, the catalyst exhibit excellent durability in both alkaline and carbonate electrolyte. Good conductivity, rich active sites, fast electron transport process and synergistic effect between Ni 3 Fe and the doped carbon together contributes to the efficient catalytic performance. This synthesis approach provides a new way to develop efficient nonprecious metal based electrocatalysts for water oxidation and other energy-related applications. Graphical abstract Image 1 Highlights • Co, N-dual doped carbon shell coated Ni 3 Fe particles was synthesized. • The catalyst exhibits enhanced OER activity in both alkaline and carbonate electrolyte. • The catalyst exhibits good stability in both alkaline and carbonate electrolyte. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • OsP 2 nanoparticles anchored on N,P-doped carbon as new catalyst is synthesized. • The interaction between OsP 2 nanoparticles and carbon is good to the catalysis. • Hydrogen evolution reaction proceeds by Volmer-Heyrovsky mechanism in acid media. • This new electrocatalyst exhibits excellent HER activity at all PH values. Abstract Exploring hydrogen evolution reaction (HER) catalysts with high activity over the wide range of pH (0–14) is of great significance, but extremely challenging. Noble-metal phosphides are newly developed electrocatalysts that can function well at all pH values. Despite the pivotal role Os compounds have played in the progress of catalytic chemistry, its phosphides have never been demonstrated to mediate the HER. Herein, we report a new OsP 2 -based electrocatalyst that consists of fine OsP 2 nanoparticles (NPs) dispersed over N,P co-doped carbon film (OsP 2 @NPC) using a combination of template and pyrolysis methods. Impressively, this novel OsP 2 @NPC exhibits improved HER activity compared with Os@NPC, with small overpotentials of 38, 54, and 70 mV at 10 mA cm−2 and Tafel slopes of 40, 82, and 67 mV dec−1, and better stability than commercial Pt/C in 0.5 M H 2 SO 4 , 1.0 M phosphate buffer solution, and 1.0 M KOH, respectively. The experimental and computational results indicate that both the unique structure of the porous interconnected network and the interaction between OsP 2 NPs and NPC contribute to the robust activity. Meanwhile, the ∼40 mV dec−1 Tafel slope in 0.5 M H 2 SO 4 and the density functional theory (DFT) calculations suggest the predominant Volmer-Heyrovsky mechanism for the OsP 2 -catalyzed HER, with electrochemical desorption of hydrogen as the rate-limiting step. This new electrocatalyst is expected to enlarge the growing family of transition metal phosphides for the HER. [ABSTRACT FROM AUTHOR]

Abstract Sulphur and nitrogen-rich carbon layers (S/N-CLs) have been derived successfully via a simple calcination for high energy applications including supercapacitor and electrocatalytic hydrogen evolution reaction (HER). The flexible working electrode was fabricated using thoroughly analyzed S/N-CLs composite as an active electrode energy material for supercapacitor and HER. The S/N-CLs composite shows a higher specific capacitance of 266 F g−1 at a current density of 0.5 A g−1 and a satisfied cycling stability with 84% capacitance retention even after 5000 cycles of galvanostatic charge-discharge. On the other hand, the synthesized S/N-CLs composite was used as an electrocatalyst for HER and it exhibits an excellent HER performance with an onset overpotential of −75 mV, and a Tafel slope of 73 mV dec−1 in 0.5 M H 2 SO 4 aqueous electrolyte. Also, the S/N-CLs composite displayed good stability and strong durability. The high electrocatalytic activity and stability of S/N-CLs composite toward HER due to the active site of a compound which may originate from the heteroatom-functional groups including N and S in the carbon structure. Overall, the high-performance supercapacitors and enhancing HER based on heteroatom-doped carbon structures could be promising in replacing traditional supercapacitors for many electronic devices and electrocatalyst for HER. Graphical abstract Unlabelled Image Highlights • Conversion of Magnolia liliiflora into S/N-CLs composite by a simple carbonization • S/N-CLs delivered a higher C s of 266 F g−1 at 0.5 A g−1 with a satisfied stability. • S/N-CLs exhibits an excellent HER performance with a Tafel slope of 73 mV dec−1. • This is the first attempt in synthesis of S/N-CLs using Magnolia liliiflora flower. • S/N-CLs will be an alternative for traditional energy storage material and electrocatalyst. [ABSTRACT FROM AUTHOR]

Herein, renewable resource‐based waste materials (used tea leaves and molasses) were utilized as inexpensive and renewable carbon sources to develop Phosphorus and Nitrogen co‐doped Carbon (PNDC) materials for supercapacitor application. A prompt, low cost, single step, green and facile microwave assisted process was utilized to prepare PNDC materials using the aforementioned biomass. Concentration of the doping elements (P and N) was altered in the resulting PNDC materials by varying the mole ratio of used tea/molasses and ammonium polyphosphate (APP) in the reaction mixture. APP served as the Phosphorus and Nitrogen source as well as the microwave absorber. Detailed characterization of all four PNDCs ‐ two derived from molasses (MOLPNDCs) and two from used tea leaves (TEAPNDCs), were performed to investigate their supercapacitor performance. These materials were characterized both physically via BET, XPS, and SEM analysis and electrochemically via cyclic voltammetry, in both 1 M H2SO4 and 6 M KOH. Pore size, surface area, and elemental compositions of each PNDC was analyzed to investigate the critical parameter for supercapacitor performance of the materials. Among all PNDCs, MOLPNDC‐1 exhibited exceptionally high specific capacitance values of 160 Fg−1 in 6 M KOH electrolyte due to highly mesoporous structure and appropriate Nitrogen content. MOLPNDC‐1 was also found to be stable under continuous cycling for 1500 cycles in both acidic and alkaline conditions. This work illustrates a single‐step, green strategy that utilizes inexpensive and renewable resource‐based precursors to develop electrode materials for use in supercapacitors. Exceptional capacitance values are achieved via carbonization of used tea and molasses which are both waste products of the food industry. The key parameters influencing the specific capacitance values of these renewable resource‐derived doped carbon materials are critically investigated. [ABSTRACT FROM AUTHOR]