Lijun He’s research while affiliated with Ningxia University and other places

Capacitive deionization (CDI) is a promising desalination technique that gains more and more attentions worldwide in recent years due to its high efficiency and feasibility. In this work, the sulfuric acid functionalized activated carbon (FAC) is proposed as electrode for CDI. By compared to pristine AC, FAC electrode shows an improved microspores volume from 0.17 to 0.22 m3 g-1 and therefore a high electrosorption capacity of 3.54 mg g-1 as well as a charge efficiency of 0.21. Furthermore, the FAC electrode follows the Langmuir isotherm, indicating the monolayer adsorption. Besides, the pseudo-first-order can describe the adsorption kinetics of FAC electrode as compared to other kinetics models. Additionally, the FAC electrode can be regenerated very well.

In this work, the sulfonated reduced graphene oxide (SRGO) was synthesized and proposed as an enhanced anode material for lithium ion battery (LIB). The result shows that the SRGO has an improved battery performance (i.e., ∼341.7 mAh/g and ∼ 190.6 mAh/g corresponds to SRGO and RGO at the 100th cycle with a current density of 200 mA/g) and superior cycling stability compared with pristine reduced graphene oxide (RGO). These are attributed to the improved specific surface area (448.35 m2/g) and conductivity (2.5 × 10-4S/m). Further, the SRGO exhibits good rate capability and excellent energy density at various current densities ranging from 50 mAh/g to 2000 mAh/g, suggesting that SRGO could be a promising anode material for high capacity LIB.

In this work, the capacitive deionization (CDI) performance of a single-walled carbon nanotube (CNT) electrode has been studied from the point view of charge efficiency theory. It is revealed here that the charge efficiency of a CNT electrode is strongly dependent upon the cell voltage and solution concentration. Either the high cell voltage or the low ionic strength results in a high charge efficiency, implying that CDI is expected to be a promising technique for an aqueous solution with low ionic strength. Additionally, it is found that the high decay constant and high electrical double-layer capacity are beneficial to enhance electrosorption performance.

Two-dimensional SnO2 nanomaterials hold great potential for new advanced applications, such as solar cells, batteries, and gas sensors. Here, we report a large-scale synthesis of high-quality ultrathin SnO2 nanosheets from ball-milled commercial SnO2 powder under mild hydrothermal conditions. These nanosheets show a graphene-like morphology with large planar area, ultrathin thickness (2–5 nm), and high percentage of surface atoms. Dissolution/hydrolysis/precipitation is proposed as a growth mechanism.

Low cost and abundant natural ilmenite (FeTiO3) is used as raw materials for preparing TiO2-carbon nanocomposites. A new method combining several traditional techniques (ball milling, high-temperature annealing and chemical leaching) is proposed in this paper. The resulting composite is a spherical material, consisting of nanosized TiO2 particles (with a size range of 5-80 nm) homogeneously distributed in carbon (amorphous) matrix. Its electrochemical performance is evaluated by using coin-type cells versus metallic lithium in an enlarged potential window of 0.01-3.0 V. A high specific charge capacity of 722 mA h g(-1) is obtained at a current density of 33.6 mA g(-1). Moreover, the TiO2-carbon nanocomposite exhibits excellent rate capability, even at a high current density of 10.8 A g(-1), the specific charge capacity is 41 mA h g(-1).

Based on the particle morphology of beryllium (Be) powders produced by impact attrition, a physics model has been established for describing the particle size distribution, which has only one parameter with the definite physical meaning. Two important internal mechanisms are considered: firstly, the distribution of existing state of particles with different original kinetic energy should obey the Maxwell-Boltzmann distribution after impacting, which means that big particles are unstable for their being at higher energy level, therefore they are easy to be fractured into smaller pieces in impact attrition process, and this influencing factor can be described as the negative exponential function of particles size; secondly, the tendency to remain low surface energy requires that Be powders should keep big volume as much as possible, and this influencing factor is defined as the cube function of particles size. The actual size distribution of Be particles is resulted from the competition between these two factors. Calculating result from the model is in good agreement with data from measurement.

Sulphonated reduced graphene oxide (SRGO) is self-assembled onto carbon fibre cloth (CFC) by electrophoresis deposition as a composite (CFC–SRGO) electrode for high-performance capacitive deionization (CDI). The resulting CFC–SRGO composite shows a cross-linked nanotubular structure and the individual carbon fibre is fully encapsulated by SRGO nano-sheets, forming a cylindrical-shell microstructure. The electrosorption performance of the CFC–SRGO composite electrode is determined by carrying out a batch-mode electrosorption experiment, showing a great improvement in charge efficiency of more than twice that of a bare CFC electrode. Remarkably, this result is comparable with that of membrane enhanced capacitive deionization. Further, the low exponential decay constant of the CFC–SRGO composite electrode derived from the electrosorption kinetics demonstrates that the deposited SRGO favors a decrease in the internal electrode resistivity and therefore improves the ion electrosorption rate which contributed to the enhanced charge efficiency significantly. Another possible reason accounting for the high charge efficiency of the CFC–SRGO electrode is that the functionalized SRGO is analogous to a cation-exchange membrane which can block the co-ions during electrosorption. In addition, the electrosorption isotherm of the CFC–SRGO film follows Langmuir adsorption, indicating the monolayer adsorption mechanism. Meanwhile, the thermodynamic analyses imply that the electrosorption of salt ions onto the CFC–SRGO electrode is driven by a physisorption process.

A novel, environmental-friendly approach for the reduction of graphene oxide (GO) by means of incorporating visible-light sensitive TiO2 and steady state visible-light irradiation was undertaken. Some potential applications of the resultant TiO2-graphene composites as water treatment technique, such as electrosorption and dissolved organic matter removal, have been demonstrated as well.

Large scale reduced graphene oxide (RGO) with sulfonic acid groups (SRGO) has been synthesized by a one-step facial method for high performance electrochemical capacitors (ECs). The as-prepared SRGO shows an enhanced specific surface from 254 to 434 m2 g−1 and bulk conductivity from 2 × 10−4 to 2.5 × 10−4 S m compared with that of pristine RGO. An asymmetric EC was assembled with SRGO as the working electrode and Pt as the counter electrode immersed in a 1 M neutral aqueous Na2SO4 solution. The results showed that a maximum specific capacitance of 130 F g−1 was achieved by the SRGO, which is much higher than that of pristine RGO. The SRGO also exhibits a high rate capability and superior cycling stability of more than 99% retention of the specific capacitance after 1000 cycles. Furthermore, it also exhibits excellent specific energy and power densities of 14.6 W h kg−1 and 50 W kg−1 at a current density of 100 mA g−1, respectively. These results suggest that our SRGO material could be a very promising and versatile building block for carbon-based materials as electrodes towards the next generation of high-performance ECs.

A series of Al2O3 substituted manganese oxide ceramic compounds, Ni0.6Si0.2Mn2.2-xAlxO4(0 ≤ x ≤ 0.6), were prepared by solid-state reaction route. The phase composition, microstructure, and electrical properties of compounds were studied. The results revealed that all the compounds were composed of cubic spinel structure without any other oxides. Besides they exhibited a linear relationship between logarithm of electrical resistivity (ln ρ) and reciprocal of absolute temperature (1/T) over a temperature ranging from room temperature to 300°C, which indicated a negative temperature coefficient (NTC) characteristic. The B25/85 constant was found to increase with the increase of Al2O3 content. The B25/85 values of the NTC Ni0.6Si0.2Mn2.2-xAlxO4 thermistors for x = 0,0.1,0.2,0.3,0.4, and 0.6 were 4581, 4612, 4680, 4875, and 5089 K, respectively. Finally, a new method to produce one meter long continuous fire wire sensors was also proposed.