Free-standing porous carbon electrodes derived from wood for high-performance Li-O2 battery applications

Porous carbon materials are widely used in particulate forms for energy applications such as fuel cells, batteries, and （super） capacitors. To better hold the particles together, polymeric additives are utilized as binders, which not only increase the weight and volume of the devices, but also cause adverse side effects. We developed a wood-derived, free-standing porous carbon electrode and successfully applied it as a cathode in Li-O2 batteries. The spontaneously formed hierarchical porous structure exhibits good performance in facilitating the mass transport and hosting the discharge products of Li202. Heteroatom （N） doping further improves the catalytic activity of the carbon cathode with lower overpotential and higher capacity. Overall, the Li-O2 battery based on the new carbon cathode affords a stable energy efficiency of 65% and can be operated for 20 cycles at a discharge depth of 70%. The wood-derived free-standing carbon represents a new, unique structure for energy applications.

An oxygen reduction sensor based on a novel type of porous carbon composite membrane electrode

The development of a simple, efficient and sensitive sensor for dissolved oxygen is proposed using a novel type of porous carbon composite membrane/glassy carbon electrode based on the low-cost common filter paper by a simple method. The resulting device exhibited excellent electrocatalytic activities toward the oxygen reduction reaction. Scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and electrochemical measurements demonstrated that the porous morphology and uniformly dispersed Fe;C nanoparticles of the PCCM play an important role in the oxygen reduction reaction. A linear response range from 2mmol/L up to 110 mmol/L and a detection limit of 1.4 mmol/L was obtained with this sensor. The repeatability of the proposed sensor,evaluated in terms of relative standard deviation, was 3.0%. The successful fabrication of PCCM/GC electrode may promote the development of new porous carbon oxygen reduction reaction material for the oxygen reduction sensor.

Porous carbon globules with moss-like surfaces from semi-biomass interpenetrating polymer network for efficient charge storage

The bio-nanotechnological fabrication of high-surface-area carbons has attracted widespread interest in supercapacitor applications by using readily-available natural products as raw materials or bio-templates,and is expected to refine on pore accessibility for compact energy storage. Here, a renovated design strategy of semi-biomass interpenetrating polymer network(IPN) derived carbon is demonstrated through physically knitting the biomacromolecule(sodium alginate, SA) polymeric chains into the highly crosslinked resorcinol-formaldehyde(RF) network and subsequent thermochemical conversion. Moleculelevel interlacing forces in such IPN efficiently relieve the RF skeleton shrinkage when producing carbon,while the other SA network addresses the macrophase separation issue to sacrifice as an in-knitted porogen and a morphology-directing agent. As a result, porous carbon globules are equipped with moss-like surfaces and interconnected pore architecture for high accessible electrode surface(1013 m^(2)/g), and efficient electrochemical responses are reached with the specific capacitance of 312 F/g at 1 A/g. Taking the advantage of 9 mol/kg NaClO_(4) complex-solvent electrolyte, the voltage window is extended to 2.4 V,endowing the two-electrode device with the high energy delivery of 32.3 Wh/kg at 240 W/kg.

Recovery and reuse of floc sludge for high-performance capacitors

In this paper,floc sludge was transformed into porous carbon matrix composites by acidification and KOH activation at high temperature and used as an electrode material for application in capacitors.The effects of different treatment processes on the electrochemical properties of sludge materials were compared.The results of electrochemical tests showed that the sludge electrode exhibited excellent energy storage performance after HNO3 acidification and KOH activation with a mass ratio of 3:1(KOH/C).The specific capacitance of the sludge electrode reached 287 F/g at a current density of 1 A/g.In addition,the sludge electrode material showed excellent cycle stability(specific capacity retained at 93.4%after 5000 cycles at 5 A/g).Based on XRD,FTIR,SEM,TEM,and BET surface analysis,the morphology of sludge electrode materials can be effectively regulated by chemical pretreatment.The best-performing material showed a 3D porous morphology with a large specific surface area(2588 m^(2)/g)and optimal pore size distribution,improving ion channels and charge conductivity.According to the life cycle assessment of floc sludge utilization,it reduced the resource consumption and toxicity risk by more than 90%compared with ordinary sludge disposal processes.This work provided a cost-effective and eco-friendly sludge reuse method and demonstrated the application potential of sludge-based materials in high-performance supercapacitors.