Sampling ultrasmall volumes of liquids for analysis is essential in a number of fields from cell biology to microfluidics to nanotechnology and electrochemical energy storage. In this article, we demonstrate the possibility of using nanometer-sized quartz pipettes with a layer of carbon deposited on the inner wall for sampling attoliter-to-picoliter volumes of fluids and determining redox species by voltammetry and coulometry. Very fast mass-transport inside the carbon-coated nanocavity allows for rapid exhaustive electrolysis of the sampled material. By using a carbon pipette as the tip in the scanning electrochemical microscope (SECM), it can be precisely positioned at the sampling location. The developed device is potentially useful for solution sampling from biological cells, micropores, and other microscopic objects.

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A freestanding 3D graphdiyne–cobalt nitride (GDY/Co2N) with a highly active and selective interface is fabricated for the electrochemical nitrogen reduction reaction (ECNRR). Density function theory calculations reveal that the interface‐bonded GDY contributes an unique p‐electronic character to optimally modify the Co‐N compound surface bonding, which generates as‐observed superior electronic activity for NRR catalysis at the interface region. Experimentally, at atmospheric pressure and room temperature, the electrocatalyst creates a new record of ammonia yield rate (YNH3 ) and Faradaic efficiency (FE) of 219.72 μg h−1 mgcat.−1 and 58.60 %, respectively, in acidic conditions, higher than reported electrocatalysts. Such a catalyst is promising to generate new concepts, new knowledge, and new phenomena in electrocatalytic research, driving rapid development in the field of electrocatalysis.