Nowadays, metal oxide semiconductors (MOS)-reduced graphene oxide (rGO) nanocomposites have attracted significant research attention for gas sensing applications. Herein, a novel composite material is synthesized by combining two p-type semiconductors, i.e., Cu2O and rGO, and a p-p-type gas sensor is assembled for NO2 detection. Briefly, polypyrrole-coated cuprous oxide nanowires (PPy/Cu2O) are prepared via hydrothermal method and combined with graphene oxide (GO). Then, the nanocomposite (rGO/PPy/Cu2O) is obtained by using high-temperature thermal reduction under Ar atmosphere. The results reveal that the as-prepared rGO/PPy/Cu2O nanocomposite exhibits a maximum NO2 response of 42.5% and is capable of detecting NO2 at a low concentration of 200 ppb. Overall, the as-prepared rGO/PPy/Cu2O nanocomposite demonstrates excellent sensitivity, reversibility, repeatability, and selectivity for NO2 sensing applications.

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We report a simple fabrication of a gas sensor using a nanohybrid composite of reduced graphene oxide/cuprous oxide (rGO/Cu2O). The deoxidation of GO occurs meanwhile with the synthesis of Cu2O. The Cu2O component of the nanohybrid material has a linear morphology and a micron size, which is homogeneously mixed with rGO. The rGO/Cu2O gas sensor can effectively detect ppm level of NO2 gas, showing an outstanding reusability. Because rGO/Cu2O has a large specific surface area, it is more conducive to gas adsorption on its surface. Its good effect on detecting NO2 proves that the sensor has good commercial prospects.

During the transition towards a low carbon energy system, and as a result of the increasing penetration of renewable energy generation, ancillary services play an important role in ensuring the security and economics of power system operation. An integrated energy service provider (IESP), with the energy coupling and storage devices inside, can flexibly participate in electric energy markets and ancillary service markets. In this paper, a mixed-integer optimization problem is formulated to determine the optimal operating strategy for the IESP with ancillary service provision. First, the mathematical model of a regional integrated energy system (RIES) is established, including energy coupling devices and energy storage devices. Then, an optimization model for the IESP operation is formulated with the objective of maximizing daily operation profit, and the corresponding optimal capacity of ancillary service provision from the IESP is attained. Finally, case studies of an RIES are carried out to demonstrate the feasibility and effectiveness of the proposed method, and the impacts of the IESP with ancillary service provision on operational characteristics and economic benefits are analyzed.

In this study, nickel nanowires (Ni-NWs) were first grown by chemical method and then graphene was grown on the as-obtained Ni-NWs by CVD route to yield graphene nanotubes (GNTs). The GNTs were then hydrothermally combined with ZnO to construct a gas sensor for detection of NO2. The as-prepared GNT@ZnO sensor displayed high sensitivity towards the detection of NO2 reaching up to 47.5% per 50 ppm NO2. In addition, the sensor exhibited relatively fast response time of 300 s and recovery time of around 200 s under UV light. The sensor also showed good repeatability, making it promising for future applications.