Not only in electrochemistry but also in biology and in membrane transport, localized processes at solid-liquid or liquid-liquid interfaces play an important role at defect sites, pores, or individual cells, but are difficult to characterize by integral investigation. Scanning electrochemical microscopy is suitable for such investigations. After two decades of development, this method is based on a solid theoretical foundation and a large number of demonstrated applications. It offers the possibility of directly imaging heterogeneous reaction rates and locally modifying substrates by electrochemically generated reagents. The applications range from classical electrochemical problems, such as the investigation of localized corrosion and electrocatalytic reactions in fuel cells, sensor surfaces, biochips, and microstructured analysis systems, to mass transport through synthetic membranes, skin and tissue, as well as intercellular communication processes. Moreover, processes can be studied that occur at liquid surfaces and liquid-liquid interfaces.

It is essential to impart the thermal stability, high sensitivity, self-healing, and transparent attributes to the emerging wearable and stretchable electronics. Here, a facile solvent replacement strategy is exploited to introduce ethylene glycol/glycerol (Gly) in hydrogels for enhancing their thermal sensitivity and stability synchronously. For the first time, we find that the solvent plays a key role in the thermal sensitivity of hydrogels. By adjusting the water content in hydrogels using a simple dehydration treatment, the thermal sensitivity is raised to 13.1%/°C. Thanks to the ionic transport property and water–Gly binary solvent, the organohydrogel achieves an unprecedented thermal sensitivity of 19.6%/°C, which is much higher than those of previously reported stretchable thermistors. The mechanism for the thermal response is revealed by considering the thermally activated ion mobility and dissociation. The stretchable thermistors are conformally attached on curved surfaces for the practical monitoring of minute temperature change. Notably, the uncovered Gly-organohydrogel avoids drying and freezing at 70 and −18 °C, respectively, reflecting the excellent antidrying and antifreezing attributes. In addition, the organohydrogel displays ultrahigh stretchability (1103% strain), self-healing ability, and high transparency. This work sheds light on fabricating ultrasensitive and stretchable temperature sensors with excellent thermal stability by modulating the solvent of hydrogels.

Developing high-active and low-cost bifunctional materials for catalyzing the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) holds a pivotal role in water splitting. Therefore, we present a new strategy to form NiS/NiP heterostructures. The as-obtained NiS/NiP/carbon cloth (CC) requires overpotentials of 111 mV for the HER and 265 mV for the OER to reach a current density of 20 mA cm, outperforming their counterparts such as NiS and NiP under the same conditions. Additionally, the NiS/NiP/CC electrode requires a 1.67 V cell voltage to deliver 10 mA cm in a two-electrode electrolysis system, which is comparable to the cell using the benchmark Pt/C||RuO electrode. Detailed characterizations reveal that strong electronic interactions between NiS and NiP, abundant active sites, and smaller charge-transfer resistance contribute to the improved HER and OER activity.

In planar n-i-p heterojunction perovskite solar cells, the electron transport layer (ETL) plays important roles in charge extraction and determine the morphology of the perovskite film. Here, we report a solution-processed carbon quantum dots (CQDs)/TiO composite that has negligible absorption in the visible spectral range, a very attractive feature for perovskite solar cells. Using this novel CQDs/TiO ETL in conjunction with a planar n-i-p heterojunction, we achieved an unprecedented efficiency of ∼19% under standard illumination test conditions. It was found that a CQDs/TiO combination increases both the open circuit voltage and short-circuits current density as compared to using TiO alone. Various advanced spectroscopic characterizations including ultrafast spectroscopy, ultraviolet photoelectron spectroscopy, and electronic impedance spectroscopy elucidate that the CQDs increases the electronic coupling between the CHNHPbICl and TiO ETL interface as well as energy levers that contribute to electron extraction.