The modification methods of carbon material and their effect on the CDI performance were reviewed.

Heteroatom doped hierarchically porous carbon materials are considered as promising candidates for high performance capacitive deionization and supercapacitor applications. However, the development of carbons simultaneously having both a reasonable polar surface and a hierarchically porous structure via a flexible synthetic strategy is critical but still a great challenge. Herein, a facile and effective strategy is presented for the preparation of N and P dual-doped hierarchically porous carbon networks by one-pot carbonization of a rationally designed precursor that was built using a metal–organic gel with a zinc ion metallic cluster and nitrogen/phosphorus chelate ligands. Due to the abundant exposed polar surface groups and the highly developed interconnected macro-/meso-/microporous structure, the optimal sample delivers a high specific capacitance of 373 F g⁻¹ at a current density of 1 A g⁻¹ and retains 270 F g⁻¹ at 100 A g⁻¹ with a capacitive retention of 72.3%. Furthermore, the symmetric supercapacitors assembled in aqueous and PVA/KOH solid electrolytes exhibit excellent energy outputs of 38.5 and 7.5 W h kg⁻¹, respectively. For capacitive deionization, the sample displays a superior salt adsorption capacity of 7.7, 10.3 and 18.1 mg g⁻¹ in NaCl solution with an initial concentration of 250 mg L⁻¹ at applied voltages of 1, 1.2 and 1.4 V, respectively. Additionally, kinetics studies and density functional theory simulations reveal that N/P dual-doping not only reliably introduces pseudocapacitance, but also greatly enhances the chemisorption of Na and Cl, resulting in a remarkable electrochemical performance. This work provides a new insight into the relationship between polar surface/structural engineering and the capacitive performance of the designed materials.

Prussian blue analogues (PBAs) have recently been proposed as electrode materials for efficient capacitive deionization (CDI). However, there is a conflict between the desalination capacity and stability for single-component bimetallic PBAs, making it difficult to simultaneously achieve high desalination capacity and recyclability. To overcome this limitation, this study made an attempt to synthesize the core@shell heterostructured CuFe@NiFe PBA by enclosing a high-capacity CuFe PBA with the stable NiFe PBA shell. The desalination tests showed that the CuFe@NiFe PBA had a higher desalination capacity with less energy consumption compared with the sole core material, associated with the more rapid intercalation reactions of Na ions due to the unique core–shell heterostructure. Furthermore, the recyclability of the CuFe@NiFe PBA was improved significantly, attributed to the protective effect of the NiFe PBA against the irreversible structural change of the CuFe PBA during the long-term operation. The electrochemical and material measurements revealed that the desalination and regeneration processes were governed by the redox of the Fe³⁺/Fe²⁺ couple and Cu²⁺/Cu⁺ couple while the Ni³⁺/Ni²⁺ couple was electrochemically inactive for the CuFe@NiFe PBA. Consequently, the core–shell heterostructured CuFe@NiFe PBA would be a promising material for application in a CDI system.

Because of rapid growth in population and industrialization, worldwide ethanol demand is increasing continuously. The first-generation and second-generation biofuels are unable to meet the global demand of bioethanol production because of their primary value of food and feed. Therefore, algae are among the most potentially significant sources of sustainable biofuels in the future of renewable energy because of the accumulating high starch/cellulose and because they are widely distributed in nature. The focus of this paper is to review the production and recent advances in research and development in the algae bioethanol, including pretreatment, hydrolysis, and fermentation of algae biomass. Despite the many developments made in the recent years, commercialization of algal bioethanol remains challenging chiefly because of the techno-economic constraints. Technological breakthroughs in all major aspects must be overcome before it can be a successfully large-scale and commercialized product. Copyright © 2014 John Wiley & Sons, Ltd.

We report phosphorus (P)-doped activated carbon (AC) as a highly active catalyst for the oxygen reduction reaction (ORR) in air-cathode microbial fuel cells (MFCs). P-doped AC was prepared by impregnating AC with H₃PO₄ (1 M) and then heating at 200 °C, 400 °C, 600 °C, 800 °C and 1000 °C, respectively in the presence of nitrogen. The pretreatment of AC increased the power density of MFCs by 75% from 730 ± 23 mW m⁻² (RAW-SP, untreated AC) to 1278 ± 56 mW m⁻² (SP-800, heated at 800 °C). X-ray photoelectron spectroscopy (XPS) analysis confirmed the successful doping of P in all treated samples, and the introduction of oxygen-containing groups contributed to the increase of power densities and ORR performance. Raman spectra analysis indicated that the AC structure was deformed by the doped P atom. According to X-ray diffraction (XRD) and transmission electron microscopy (TEM), the treated samples revealed a higher graphitization degree than the control. The results of electrochemical impedance spectroscopy (EIS) also showed that the introduction of the P heteroatom reduced the total resistance, which contributed to the improved electrochemical performance. However, high temperature could destroy the AC's structure, which led to the decline of BET surface area and micropore volume. Thus, P-doped AC would be a promising electrocatalyst for the ORR in MFCs.