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In this work, a simple synthesis strategy has been developed for the preparation of nitrogen- and sulfur-codoped porous carbon nanosheets (N/S-CNS) as a cathode catalyst for microbial fuel cells (MFCs). The as-prepared N/S-CNS showed favorable features for electrochemical energy conversion such as high surface area (1004 m(2) g(-1)), defect structure, and abundant exposure of active sites that arose primarily from porous nanosheet morphology. Benefiting from the unique nanostructure, the resulting nanosheets exhibited effective electrocatalytic activity toward oxygen reduction reaction (ORR). The onset potential of the N/S-CNS in linear-sweep voltammetry was approximately -0.05 V vs Ag/AgCl in neutral phosphate buffer saline. Electrochemical impedance spectroscopy showed that the ohmic and charge-transfer resistance of the codoped catalyst were 1.5 and 14.8 Ω, respectively, both of which were lower than that of platinum/carbon (Pt/C). Furthermore, the electron-transfer number of the N/S-CNS was calculated to be ∼3.5, suggesting that ORR on the catalyst proceeds predominantly through the favorable four-electron pathway. The MFC with N/S-CNS as a cathode catalyst generated current density (6.6 A m(-2)) comparable to that with Pt/C (7.3 A m(-2)). The high durability and low price indicate that N/S-CNS can be a competitive catalyst for applications of MFCs.

Cost-effective cathode catalysts are critical to the development of microbial fuel cell (MFC) technology. Herein, a synthesis route is presented to improve the nitrogen content and nitrogen functionality in the nitrogen-doped activated carbon (AC) as a low cost and efficient catalyst for oxygen reduction reaction (ORR). It was demonstrated that key factors for successful nitrogen doping were the proper pretreatment with acidic and alkaline solutions consecutively and the use of a solid-state nitrogen precursor. The AC pretreated with both acidic and alkaline solutions resulted in a nitrogen content of 8.65% (atom %) (in which 5.56% is pyridinic-N) on its surface, and exhibited an outstanding electrocatalytic activity for ORR in both electrochemical and MFC tests. A good agreement between pyridinic-N content and ORR activity was observed, indicating that pyridinic-N is the most active site for ORR in the nitrogen-doped AC. The pretreated nitrogen-doped AC catalysts resulted in a higher maximum power density than the untreated AC and the commercial Pt/C (10% Pt) catalysts. The exceptional performance associated with the advantages, such as simple and convenient preparation procedure, easily obtained raw materials, and low cost, makes the pretreated nitrogen-doped AC promising for the ongoing effort to scale up MFCs.

Sulfur has received increasing attention as a cathode material for lithium-sulfur (Li-S) batteries due to its high theoretical specific capacity. However, the commercialization of Li-S batteries is limited by the challenges of poor electrical conductivity of sulfur, dissolution of the polysulfide intermediates into the electrolyte, and volume expansion of sulfur during cycling. Herein, we report the fabrication of novel-structured porous carbon microspheres with a controllable multi-modal pore size distribution, i.e., a combination of interconnected micropores, mesopores and macropores. Cathodes made of sulfur infiltrated in such a hierarchical carbon framework provide several advantages: (1) a continuous and high surface area carbon network for enhanced electrical conductivity and high sulfur loading; (2) macropores and large mesopores bridged by small mesopores to provide good electrolyte accessibility and fast Li ion transport and to accommodate volume expansion of sulfur; and (3) small mesopores and micropores to improve carbon/sulfur interaction and to help trap polysulfides. An initial discharge capacity at 1278 mA h g(-1) and capacity retention at 70.7% (904 mA h g(-1)) after 100 cycles at a high rate (1 C) were achieved. The material fabrication process is relatively simple and easily scalable.

A cost-effective route for the preparation of Fe(3) C-based core-shell structured catalysts for oxygen reduction reactions was developed. The novel catalysts generated a much higher power density (i.e., three times higher at R(ex) of 1 Ω) than the Pt/C in microbial fuel cells. Furthermore, the N-Fe/Fe(3)C@C features an ultralow cost and excellent long-term stability suitable for mass production., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Conversing CO2 into value‐added chemicals endows electrochemical CO2 reduction reaction (CO2RR) with the potential to tackle over issues induced by the increased CO2 level in the atmosphere. The associated technological viability of this process is highly dependent on exploring efficient electrocatalysts. In this work, we successfully synthesized nitrogen and sulfur co‐doped carbon nanosheets (NS‐CNSs), which are comprehensively characterized by a variety of characterization techniques. When used as the catalyst for CO2RR, the NS‐CNSs exhibit remarkably high catalytic activity and selectivity with a Faradaic efficiency of ∼85.4 % for CO production and long‐term durability. The superior performance of this material majorly originates from the unique nanosheets structure with large porosity and the co‐doped S and N in the nanosheets, which exposed larger electrochemical activity surface areas and more active sites for promoting CO2 reduction. [ABSTRACT FROM AUTHOR]

We report a straightforward strategy to design efficient N doped porous carbon (NPC) electrocatalyst that has a high concentration of easily accessible active sites for the CO2 reduction reaction (CO2RR). The NPC with large amounts of active N (pyridinic and graphitic N) and highly porous structure is prepared by using an oxygen‐rich metal–organic framework (Zn‐MOF‐74) precursor. The amount of active N species can be tuned by optimizing the calcination temperature and time. Owing to the large pore sizes, the active sites are well exposed to electrolyte for CO2RR. The NPC exhibits superior CO2RR activity with a small onset potential of −0.35 V and a high faradaic efficiency (FE) of 98.4 % towards CO at −0.55 V vs. RHE, one of the highest values among NPC‐based CO2RR electrocatalysts. This work advances an effective and facile way towards highly active and cost‐effective alternatives to noble‐metal CO2RR electrocatalysts for practical applications. [ABSTRACT FROM AUTHOR]

It is of increasing importance to explore new low-cost and high-activity electrocatalysts for oxygen reduction reaction (ORR), which have had a substantial impact across a diverse range of energy conversion system, including various fuel cell and metal-air batteries. Although engineering carbon nanostructures have been widely explored as a candidate class of Pt-based ORR electrocatalysts owing to their proved high activity, outstanding stability, and ease of use, there still remains a daunting challenge to develop high activity metal-free electrocatalysts in pH-universal electrolyte system. Here, a reliable and controllable route amenable to prepare nitrogen-doped porous carbon (NPC) with high yields and exceptional quality is described. The as-prepared NPC shows advantages of high activity, high durability, and methanol-tolerant as an efficient pH-universal electrocatalyst for ORR, showing comparable or even better activity as compared with the commercial Pt/C catalysts not only in alkaline media but also in acidic and neutral electrolyte. Systematic electrochemical studies, combining with density functional theory calculation, demonstrate the unique nitrogen-doping species and favorable pores in the as-designed NPC synergistically contribute to the significantly improved catalytic activity in pH-universal medium. The present work potentially presents an important breakthrough in developing ORR electrocatalysts for various fuel cells. [ABSTRACT FROM AUTHOR]

A one-pot/one-step synthesis strategy was developed for the preparation of a nitrogen-doped carbon nanoarchitecture with graphene-nanosheet growth on the inner surface of carbon nanotubes (CNTs). The N-graphene/CNT hybrids exhibit outstanding electrocatalytic activity for several important electrochemical reactions as a result of their unique morphology and defect structures, such as high but uniform nitrogen doping, graphene insertion into CNTs, considerable surface area, and the presence of iron nanoparticles. The high-yield synthetic process features high efficiency, low-cost, straightforward operation, and simple equipment. [ABSTRACT FROM AUTHOR]

Abstract: Hydrogen production in microbial electrolysis cells (MECs) is a promising approach for harvesting valuable energy products from organic wastes. Catalysts for proton reduction play a central role in decreasing energy input and increasing hydrogen production rates. Here, a novel nitrogen-containing core–shell-structured catalyst N–Fe/Fe3C@C was prepared and used to modify cathode electrodes in an MEC. The new catalyst consists of iron-based composite (Fe/Fe3C) nanorods as the core and graphite carbon as the shell. The performance of hydrogen production and catalyst stability were investigated. The new catalyst significantly improved hydrogen production compared with unmodified cathode and carbon nanotubes. Although not as efficient as platinum catalysts, a great advantage of the N–Fe/Fe3C@C is its extremely low cost (less than 5% of the Pt/C catalyst), suggesting its promise for large-scale MEC applications. [Copyright &y& Elsevier]

Potassium-Ion Hybrid Capacitors: Fast Redox Kinetics in Bi-Heteroatom Doped 3D Porous Carbon Nanosheets for High-Performance Hybrid Potassium-Ion Battery Capacitors (Adv. Keywords: fast kinetics; porous carbon nanosheets; potassium-ion hybrid capacitors; sulfur and nitrogen codoped Fast kinetics, porous carbon nanosheets, potassium-ion hybrid capacitors, sulfur and nitrogen codoped. [Extracted from the article]

Conversing CO2 into value‐added chemicals endows electrochemical CO2 reduction reaction (CO2RR) with the potential to tackle over issues induced by the increased CO2 level in the atmosphere. The associated technological viability of this process is highly dependent on exploring efficient electrocatalysts. In this work, we successfully synthesized nitrogen and sulfur co‐doped carbon nanosheets (NS‐CNSs), which are comprehensively characterized by a variety of characterization techniques. When used as the catalyst for CO2RR, the NS‐CNSs exhibit remarkably high catalytic activity and selectivity with a Faradaic efficiency of ∼85.4 % for CO production and long‐term durability. The superior performance of this material majorly originates from the unique nanosheets structure with large porosity and the co‐doped S and N in the nanosheets, which exposed larger electrochemical activity surface areas and more active sites for promoting CO2 reduction. [ABSTRACT FROM AUTHOR]

It presents the scalable salt-templated synthesis of two-dimensional porous fluorine-doped carbon (FC) nanosheets with the high active sites and larger special surface area, which shows impressive oxygen reduction reaction (ORR) activities. The synergistic effect of fluoride doping and defects provided more density of active sites in carbon material. It may open up a promising avenue for developing electrocatalysts with high catalytic activity and high stability for electrolyzed application. • Two-dimensional porous fluorine-doped carbon (FC) nanosheets. • Long-term durability and the large active surface area. • Remarkably enhanced oxygen electrocatalytic performance. We present the scalable salt-templated synthesis of two-dimensional porous fluorine-doped carbon (FC) nanosheets. Due to the larger special surface area (1031 m2 g−1) and high active sites, FC-900 (pyrolyzed at 900 °C) shows impressive oxygen reduction reaction (ORR). The synergistic effect of fluoride doping and defects provides richer density of active sites in these nanosheets. When the samples are further calcined at 900 °C for different hours, the ORR activity of the resulting samples shows a little improvement, indicating the influence of the defects on the ORR performance is much inferior to the doped fluorine. The formation of FC structures is beneficial to the ORR activity, and supported by First-principles density functional theory. The results reveal F dopants and defects important role in efficient ORR electrocatalysis owing to the synergistic effect, which is important for comprehending the origin of ORR, and it is also strong evidence to search advanced carbon-based catalysts. [ABSTRACT FROM AUTHOR]