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In this study, we have constructed ZnCr-LDH/g-C3N4 composite photocatalysts via in-situ synthesis approach. This composite material was used as catalyst interlayer of BPM to promote water dissociation. Results indicated that the combination of ZnCr-LDH and g-C3N4 could effectively improve the photoelectrocatalytic water dissociation activity. When the experiment time lasted for 1 h, the pH decreased to 1.52 in compartment 2, and increased to 13.11 in compartment 4 by using ZnCr-LDH/g-C3N4 composite catalyst.

In this study, a novel GQDs/PANI/g-C 3 N 4 ternary heterostructure was successfully designed and prepared by an in-situ polymerization and electrostatic self-assembly approach. The prepared GQDs/PANI/g-C 3 N 4 was used as interlayer of bipolar membrane (BPM) to promote water dissociation. Results revealed that GQDs/PANI/g-C 3 N 4 ternary photocatalyst exhibits excellent photoelectrocatalytic performance for water dissociation in BPM.

An Ag2O/Ag electrode was prepared through the electrochemical oxidation of sterling silver. This electrode was used as a cathodic electron acceptor in a microbial fuel cell (MFC). The Ag2O/Ag electrode was characterized by scanning electron microscopy, X-ray powder diffraction and linear sweep voltammetry. The maximum voltage output of the MFC with the Ag2O/Ag cathode was maintained at between 0.47 and 0.5 V in 100 cycles, indicating the good regenerative capacity of the Ag2O/Ag electrode. The overpotential loss for silver oxide was 0.021–0.006 V, and the maximum power output, open circuit potential and short circuit current of the MFC were 1.796 W m−3, 0.559 V and 9.3375 A m−3, respectively. The energy required for electrochemical reoxidation ranged from 40% to 55% of the energy produced by the MFC. Results indicated that the Ag2O/Ag electrode could be used as a cathodic electron acceptor in MFCs with excellent stability.

we have successfully prepared the reduced graphene oxide/protonated g-C3N4 (rGO/P-g-C3N4) composites by the electrostatic attraction of oppositely charged. The as-prepared rGO/P-g-C3N4 composites exhibit excellent photoelectrocatalytic activity for water dissociation in the bipolar membrane (BPM), this method could be conveniently applied to evaluate the catalytic performance of rGO/P-g-C3N4.

A series of nano-Mg(OH)2/graphene (Gr) composites was synthesized via simple hydrothermal method using MgSO4·7H2O and graphene oxide (GO) as precursors, hydrazine hydrate as additive. Linear sweep voltammetry tests showed that the 2# composite synthesized from 50 wt.% MgSO4·7H2O and 50 wt.% GO with a surface density of 1.5 mg cm−2 exhibited the best catalytic activity for hydrogen evolution reaction. The 2# composite was utilized as the cathodic catalyst in a microbial electrolysis cell (MEC) to facilitate hydrogen production. In the MEC tests, the nano-Mg(OH)2/Gr cathode was comparable with the Pt/C cathode in terms of current densities and energy efficiency. The hydrogen recovery, cathodic hydrogen recovery and hydrogen production rate obtained with nano-Mg(OH)2/Gr MEC were 71 ± 12%, 83 ± 9% and 0.63 ± 0.11 m3 H2 m−3 d−1, slightly higher than those obtained with the Pt/C cathode MEC. The nano-Mg(OH)2/Gr cathode exhibited good stability, and it was inexpensive (less than 1.7% of the cost of the Pt/C cathode). These results demonstrated that the nano-Mg(OH)2/Gr composite was an effective HER catalyst because of its good catalytic capacity, durability, and low price.

The effects of inoculum species, substrate concentration, temperature, and cathodic electron acceptors on electricity production of microbial fuel cells (MFCs) were investigated in terms of start-up time and power output. When inoculated with aeration tank sludge, this MFC outperformed the cell that was inoculated with anaerobic sludge in terms of start-up time and power output. After running for a certain time period, the dominant populations of the two MFCs varied significantly. Within the tested range of substrate concentration (200–1800 mg L−1), the voltage output increased and the time span of the electricity generation lengthened with increasing substrate concentration. As the temperature declined from 35 to 10 °C, the maximum power density reduced from 2.229 to 1.620 W m−3, and anodic polarization resistance correspondingly dropped from 118 to 98 Ω. The voltage output of MFC–Cu2+ was 0.447 V, which is slightly lower than that achieved with MFC–[Fe(CN)6]3− (0.492 V), thereby indicating that MFCs could be used to treat wastewater containing Cu2+ pollutant in the cathode chamber with removal of organics in anode chamber and simultaneous electricity generation.

An electrostatic self-assembly strategy for the preparation of graphene quantum dots (GQDs) attached to the surface of a glassy carbon electrode (GCE) has been developed. The GQDs were prepared by tuning the carbonization degree of citric acid and characterized by atomic force microscopy, transmission electron microscopy, Raman spectroscopy and UV–vis absorption spectroscopy. In addition, the electrochemical behaviours of hydroquinone (HQ) and catechol (CC) on the resulting modified electrodes were investigated. Under optimum conditions, the as-prepared GQDs modified electrode exhibited high electrochemical activity and good selectivity for the oxidation of HQ and CC, the linear ranges for HQ and CC were 4.0∼600 μM and 6.0∼400 μM respectively, and the detection limit was 0.40 μM and 0.75 μM, respectively. The modified electrode was also applied for the detection of real samples with satisfactory results.