Engineering of highly performing nanomaterials, capable of rapid detection of trace concentrations of gas molecules at room temperature, is key to the development of the next generation of miniaturized chemical sensors. Here, a highly performing nanoheterojunctions layout is presented for the rapid room‐temperature chemical sensing of volatile organic compounds down to ten particles per billion concentrations. The layout consists of a 3D network of nickel oxide–zinc oxide (NiO–ZnO) p–n semiconductors with grain size of ≈20 nm nanometers and a porosity of ≈98%. Notably, it is observed that the formation of the p–n heterojunctions by decoration of a ZnO nanoparticle networks with NiO increases the sensor response by more than four times while improving the lower limit of detection. Under solar light irradiation, the optimal NiO–ZnO nanoheterojunction networks demonstrate a strong and selective room‐temperature response to two important volatile organic compounds utilized for breath analysis, namely acetone and ethanol. Furthermore, these NiO–ZnO nanoheterojunctions show an inverse response to acetone from that observed for all others reducing gas molecules (i.e., ethanol, propane, and ethylbenzene). It is believed that these novel insights of the optoelectrochemical properties of ultraporous nanoheterojunction networks provide guidelines for the future design of low‐power solid‐state chemical sensors.
Quantum dots (QDs) of lead chacogenides (e.g. PbS, PbSe and PbTe) are attractive near-infrared (NIR) active materials that show great potential in a wide range of applications such as photovoltaics (PV), optoelectronics, sensors, bio-electronics and many others. The successful utilization of these functional materials requires deep understanding of their synthesis, properties and material modification process. The surface ligand plays an essential role in the production of QDs, post-synthesis modification and their integration to practical applications. Therefore, it is critically important that the influence of surface ligands on the synthesis and property of QDs is well understood for their applications in various devices. Present review elaborates the application of colloidal synthesis techniques for the preparation of lead chalcogenide based QDs. We specifically focus on the influence of surface ligands on the synthesis of QDs and their solution phase ligand exchange. Given the importance of lead chalcogenide QDs as potential light harvesters, we also pay particular attention to the current progress of these QDs in PV applications. This review concludes by providing some important research directions for the future use of lead chalcogenide QDs in solar cells.
The use of polydopamine as a nitrogen containing precursor to generate catalytically active nitrogen‐doped carbon (CNx) materials on carbon nanotubes (CNTs) is reported. These N‐doped CNx/CNT materials display excellent electrocatalytic activity toward the reduction of triiodide electrolyte in dye‐sensitized solar cells (DSSCs). Further, the influence of various synthesis parameters on the catalytic performance of CNx/CNTs is investigated in detail. The best performing device fabricated with the CNx/CNTs material delivers power conversion efficiency of 7.3%, which is comparable or slightly higher than that of Pt (7.1%) counter electrode‐based DSSC. These CNx/CNTs materials show great potential to address the issues associated with the Pt electrocatalyst including the high cost and scarcity.
Research into efficient synthesis, fundamental properties, and potential applications of phosphorene is currently the subject of intense investigation. Herein, solution-processed phosphorene or few-layer black phosphorus (FL-BP) sheets are prepared using a microwave exfoliation method and used in photoelectrochemical cells. Based on experimental and theoretical (DFT) studies, the FL-BP sheets are found to act as catalytically active sites and show excellent electrocatalytic activity for triiodide reduction in dye-sensitized solar cells. Importantly, the device fabricated based on the newly designed cobalt sulfide (CoS ) decorated nitrogen and sulfur co-doped carbon nanotube heteroelectrocatalyst coated with FL-BP (FL-BP@N,S-doped CNTs-CoS ) displayed an impressive photovoltaic efficiency of 8.31 %, outperforming expensive platinum based cells. This work paves the way for using phosphorene-based electrocatalysts for next-generation energy-storage systems.
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