Chunyang Nie

Reduced graphene oxide and activated carbon composites for capacitive deionization

In this paper, reduced graphene oxide (RGO) and activated carbon (AC) composites (GAC) have been synthesized by a facile chemical method for the capacitive removal of salt ions from brackish water. The as-prepared composites have been characterized by scanning electron microscopy, N2 adsorption–desorption and cyclic voltammetry. The GAC composite with 20 wt% graphene (GAC-20) exhibits the best electrochemical performance among all the samples, with a specific capacitance of 181 F g−1. The electrosorption capacity of the GAC-20 electrode is found to be much higher than that of the AC electrode, indicating that RGO can serve as a flexible bridge to form a “plane-to-point” (RGO-to-AC) conducting network, which is beneficial for decreasing the aggregation of AC particles, and improves the electron transfer within the composite electrode. GAC composite should be a promising candidate as an electrode material for capacitive deionization (CDI) applications.

Review on carbon-based composite materials for capacitive deionization

The last five decades have witnessed the rapid development of capacitive deionization (CDI) as a novel, low-cost and environment-friendly desalination technology. During the CDI process, salt ions are sequestered by the porous electrodes once exposed to an electric field. These electrodes, acting as an ion storage container, play a vital role during desalination. In this review, various carbon-based composite electrode materials, including carbon–carbon composites, carbon–metal oxide composites, carbon–polymer composites and carbon–polymer–metal oxide composites, are systematically presented. Applications of these carbon-based composite materials for the removal of the salt ions from solution are demonstrated and they exhibit improved CDI performances compared with pristine carbon electrodes.

Carbon aerogels electrode with reduced graphene oxide additive for capacitive deionization with enhanced performance

Carbon aerogels (CAs) electrodes with reduced graphene oxide (RGO) additive were fabricated and used as electrosorption electrodes. The capacitive deionization (CDI) performance of the CAs electrodes with different proportions of RGO was investigated. The results show that the CAs electrodes with RGO additive exhibit better electrosorption performance compared with pure CAs electrodes and an electrode with acetylene black additive, indicating that RGO can serve as a flexible bridge to form a “plane-to-point” (RGO-to-CAs) conducting network, which can improve the electron transfer within the CAs electrode. The CAs electrode with 15 wt% RGO was further used in membrane capacitive deionization which integrates ion-exchange membranes with CDI and an extremely high desalination efficiency of 98% was obtained.

Carbon nanotube and carbon nanofiber composite films grown on different graphite substrate for capacitive deionization

Abstract The carbon nanotube and carbon nanofibre (CNT–CNF) composite films are synthesized on different graphite substrate by low-pressure and low-temperature chemical vapor deposition. Scanning electron microscopy measurement and N2 adsorption experiment show that CNT–CNF composite films have network structure with optimal pore size distribution, which is beneficial to capacitive deionization. Atomic force microscopy result indicates that there is a strong correlation between the surface roughness of graphite and their thickness. Furthermore, the electrosorptive performance in salt solutions by employing as-grown CNT–CNF composite film is studied and found that the properties of the graphite substrate play a vital role in electrosorptive performance of CNT–CNF composite films by influencing their network structures.

The study of membrane capacitive deionization from charge efficiency

Abstract Membrane capacitive deionization (MCDI) is a promising technology for desalination with the potential of lowering energy consumption and treatment cost. In this paper, batch mode experiments were carried out to evaluate the charge efficiency of the MCDI process. Specifically, charge efficiency is a very functional tool to examine the double layer structure inside of porous electrode. The results show that the charge efficiency in MCDI is a function of both cell voltage and solution conductivity. Specifically, it was found that the charge efficiency was proportional to cell voltage while inversely to solution conductivity. The maximum charge efficiency (0.55) in MCDI was far less than one, indicating the high transient resistivity between membrane and carbon electrodes.

Electrical Removal Behavior of Carbon Nanotube and Carbon Nanofiber Film in CuCl2 Solution: Kinetics and Thermodynamics Study

The kinetics, thermodynamics, and isotherms during electrical removal of Cu2+ by carbon nanotube and carbon nanofiber (CNT-CNF) electrodes in CuCl2 solution were studied under different solution temperatures, initial Cu2+ concentrations, and applied voltages. The result shows that Langmuir isotherm can describe experimental data well, indicating monolayer adsorption, and higher Cu2+ removal and rate constant are achieved at higher voltage, lower initial Cu2+ concentration, and higher solution temperature. Meanwhile, the thermodynamics analyses indicate that the electrical removal of Cu2+ onto CNT-CNF electrodes is mainly driven by a physisorption process.

Kinetics and isotherm studies on electrosorption of NaCl by activated carbon fiber, carbon nanotube and carbon nanotube-carbon nanofiber composite films

In this paper, the structures of commercial activated carbon fiber (ACF), carbon nanotube (CNT) and home-made carbon nanotube-carbon nanofiber (CNT-CNF) films are characrerized and compare their electrochemical behaviors in NaCl solutions in order to study the electrosorption mechanism.