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In this study, Co 3 O 4 @MoS 2 is prepared as anodic catalytic material for microbial fuel cells (MFCs). As the mass fraction of MoS 2 is 20%, the best performance of Co 3 O 4 @MoS 2 composite catalytic material is achieved, and the addition of MoS 2 enhances both the electrical conductivity and catalytic performance of the composite catalyst. Through the structural characterization of Co 3 O 4 @MoS 2 composite catalytic material, nanorod-like Co 3 O 4 and lamellar MoS 2 interweaved and stacked each other, and the agglomeration of Co 3 O 4 is weakened. Among the four groups of single-chamber MFCs constructed, the Co 3 O 4 @MoS 2 -MFC shows the best power production performance with a maximum stable output voltage of to 539 mV and a maximum power density of up to 2221 mW/m2. Additionally, the ammonia nitrogen removal rate of the MFCs loaded with catalysts is enhanced by about 10% compared with the blank carbon cloth MFC. Overall, the findings suggest that Co 3 O 4 @MoS 2 composite catalysts can significantly improve the performance of MFCs, making them more effective for both energy production and wastewater treatment. [Display omitted] • A low-cost way for preparing Co 3 O4@MoS 2 composite catalytic materials. • The Co 3 O 4 @MoS 2 catalyst with 20% MoS 2 loading display the best electrochemical performance. • The loading of MoS 2 makes the composites exhibit better micro-morphology and catalytic properties. • The treatment of wastewater by Co 3 O 4 @MoS 2 anodic MFC shows significant enhancement of power production performance. [ABSTRACT FROM AUTHOR]

How to dispose of large quantities of hazardous shale gas drilling waste is an important worldwide problem facing the oil and gas industry. In this study, we report an environmentally friendly and low energy consumption approach (carbonization followed by activation) to convert oil-based drill sludge (OBDS) and oil-based drill cuttings (OBDCs) into biochar composites and investigate the effect of hydrofluoric acid (HF) acidification on them. The biochar composites were prepared using the OBDS, OBDCs, the mixtures of OBDS and OBDCs, and HF treatment the mixtures were named OS, OC, OSC, and OSC-HF, respectively. The characterization result of synthesized biochar composites indicated that the OSC had a larger specific surface area and a higher degree of graphitization. The composites mainly consisted of SiO 2 and BaSO 4 , except for biochar. The OSC electrode exhibited the highest oxygen evolution potential (1.72 V vs Ag/AgCl) and the lowest charge transfer resistance compared with OS, OC, and OSC-HF electrodes, implying that SiO 2 plays an important role in electrochemical performance. Using the OSC electrode as an anode, the chemical oxygen demand removal efficiency of the OBDS supernatant was 79.4 ± 0.95%. Further, the OSC electrode could maintain higher degradation efficiency and stability after the fifth reuse. The study provides a promising route for the proper disposal and resource utilization of OBDS and OBDCs and proposes a novel biochar compound as an electrode for the efficient treatment of wastewater. Moreover, this work highlights the important significance of the simultaneous resource utilization of waste and the treatment of wastewater using waste materials. [Display omitted] • A low-consumption way to treat and utilize oil-based drill sludge and cuttings. • The novel biochar-SiO 2 -BaSO 4 could be synthesized by oil-based waste as precursors. • The biochar composites display better porosity and electrochemical properties. • The biochar electrode shows 79.4% COD removal efficiency for the supernate. [ABSTRACT FROM AUTHOR]

It is considered an effective strategy to improve electrochemical performance that introducing rare elements into metal catalysts, which would provide abundant electrochemical active sites and be a benefit for redox reactions. A new Ni–Mo–P composite electrode material modified with rare earth elements (light rare earth Nd and heavy rare earth Yb) was prepared, evaluating the current density of direct current electrodeposition, the doping ratio of Yb and Nd, and the cyclic voltammetry deposition (CVD) cycle numbers on electrode structure and electrochemical performance. The results showed that the electrode has the most obvious amorphous state, the lowest hydrogen evolution overpotential (41.5 mV vs Ag/AgCl) and charge transfer resistance (15.74 Ω/cm2), and remarkable stability when the molar ratio of Yb and Nd was 8:2 and the 20 cycle numbers under the CVD condition. The electrochemical performance and characterization of the electrode showed that there was a good synergistic effect between rare earth elements (Yb, Nd) and Ni–Mo–P alloys. The oil-based drill sludge (OBDS) treatment indicated that the organic matter content is significantly reduced by using the above-modified electrode as the cathode, and the COD and petroleum removal rate can reach up to 85.4 ± 1.2% and 66.2 ± 5.9%. The effect of degradation for aliphatic hydrocarbon was better than aromatic hydrocarbons and no other intermediates are produced during the degradation, which may eventually mineralize the organic matter. This research provided technical support for the preparation of new Ni–Mo–P electrodes modified with rare earth elements and confirmed that electrocatalytic technology was a suitable method for OBDS treatment. [Display omitted] • A new rare-earth element (Yb and Nd) composite Ni–Mo–P electrode was prepared. • Investigate the effect of DC and CVD on the electrode structure and performance. • Electrochemical oxidation treatment for oil-based dill sludge. • The mechanism and process of degradation were preliminarily explored. • It provided a new idea for waste disposal of oil and gas fields with high oil. [ABSTRACT FROM AUTHOR]