Plasmonic nanostructures have been proved effective not only in catalyzing chemical reactions, but also in improving the activity of non-plasmonic photocatalysts. It is essential to reveal the synergy between the plasmonic structure and the non-plasmonic metal photocatalyst for expounding the underlying mechanism of plasmon-enhanced catalysis. Herein, the enhancement of resazurin reduction at the heterostructure of silver nanowire (AgNW) and palladium nanoparticles (PdNPs) is observed in situ by single-molecule fluorescence microscopy. The catalysis mapping results around single AgNW suggest that the catalytic activity of PdNPs is enhanced for ~ 20 times due to the excitation of localized surface plasmon resonance (LSPR) in the vicinity of the AgNW. This catalysis enhancement is also highly related to the wavelength and polarization of the excitation light. In addition, the palladium catalysis is further enhanced by ~ 10 times in the vicinity of a roughened AgNW or a AgNW–AgNW nanogap because of the improvement of catalytic hotspots. These findings clarify the contribution of plasmon excitation in palladium catalysis at microscopic scale, which will help to deepen the understanding of the plasmon-enhanced photocatalysis and provide a guideline for developing highly efficient plasmon-based photocatalysts.

Chemical and biological sensing play important roles in healthcare, environmental science, food-safety tests, and medical applications. Flexible organic electrochemical transistors (OECTs) have shown great promise in the field of chemical and biological sensing, owing to their superior sensitivity, high biocompatibility, low cost, and light weight. Herein, we summarize recent progress in the fabrication of flexible OECTs and their applications in chemical and biological sensing. We start with a brief introduction to the working principle, configuration, and sensing mechanism of the flexible OECT-based sensors. Then, we focus on the fabrication of flexible OECT-based sensors, including material selection and structural engineering of the components in OECTs: the substrate, electrodes, electrolyte, and channel. Particularly, the gate modification is discussed extensively. Then, the applications of OECT-based sensors in chemical and biological sensing are reviewed in detail. Especially, the array-based and integrated OECT sensors are also introduced. Finally, we present the conclusions and remaining challenges in the field of flexible OECT-based sensing. Our timely review will deepen the understanding of the flexible OECT-based sensors and promote the further development of the fast-growing field of flexible sensing.

Plasmonic nanostructures have been widely used for photochemical conversions due to their unique and easy-tuning optical properties in visible and near-infrared range. Compared with the plasmon-generated hot electrons, the hot holes usually have a shorter lifetime, which makes them more difficult to drive redox reactions. This review focuses on the photochemistry driven by the plasmon-generated hot holes. First, we discuss the generation and energy distribution of the plasmon-generated hot carriers, especially hot holes. Then, the dynamics of the hot holes are discussed at the interface between plasmonic metal and semiconductor or adsorbed molecules. Afterwards, the utilization of these hot holes in redox reactions is reviewed on the plasmon-semiconductor heterostructures as well as on the surface of the molecule-adsorbed plasmonic metals. Finally, the remaining challenges and future perspectives in this field are presented. This review will be helpful for further improving the efficiency of the photochemical reactions involving the plasmon-generated hot holes and expanding the applications of these hot holes in varieties of chemical reactions, especially the ones with high conversion rate and selectivity.