Mixed Cu/Cu-oxide nanoparticles are an effective catalyst for the “click” 1,3-dipolar cycloaddition between azides and terminal alkynes, featuring short reaction times, soft reaction conditions and full regioselectivity.

PEBBLES is a user-friendly software program which implements an accurate, unbiased, and fast method to measure the morphology of a population of nanoparticles (NPs) from TEM micrographs. The morphological parameters of the projected NP shape are obtained by fitting intensity models to the TEM micrograph. PEBBLES can be used either in automatic mode, where both fitting and validation are reliably carried out with minimal human intervention, and in manual mode, where the user has full control on the fitting and validation steps. Accuracy in diameter measurement has been shown to be ≲1%. When operated in automatic mode, PEBBLES can be very fast. The effective speed of 1 NP s⁻¹ has been achieved in favorable cases (packed monolayer of NPs). Since PEBBLES is based on a local modeling procedure, it successfully treats cases such as low contrast NPs, NPs with significant diffraction scattering, and inhomogeneous background which often make conventional thresholding procedures fail. PEBBLES is accompanied by PEBBLEJUGGLER, a software program for the statistical analysis of the sets of best-fit NP models created by PEBBLES. Effort has been devoted to make PEBBLES and PEBBLEJUGGLER the most user-friendly and the least user-tedious we could. PEBBLES and PEBBLEJUGGLER are available at http://pebbles.istm.cnr.it.

Defect‐engineering is a viable strategy to improve the activity of nanocatalysts for the oxygen evolution reaction (OER), whose slow kinetics still strongly limits the broad market penetration of electrochemical water splitting as a sustainable technology for large‐scale hydrogen production. High‐entropy spinel oxides (HESOs) are in focus due to their great potential as low‐cost OER electrocatalysts. In this work, electrospun HESO nanofibers (NFs), based on (Cr,Mn,Fe,Co,Ni), (Cr,Mn,Fe,Co,Zn) and (Cr,Mn,Fe,Ni,Zn) combinations, with granular architecture and oxygen‐deficient surface are produced by calcination at low temperature (600 or 500 °C), characterized by a combination of benchtop analytical techniques and evaluated as electrocatalysts for OER in alkaline medium. The variation of HESO composition and calcination temperature produces complex and interdependent changes in the morphology of the fibers, crystallinity and inversion degree of the spinel oxide, concentration of the oxygen‐vacancies, cation distribution in the lattice, which mirror on different electrochemical properties of the fibers. The best electrocatalytic performance (overpotential and Tafel slope at 10 mA cm⁻²: 360 mV and 41 mV dec⁻¹, respectively) pertains to (Cr_1/5Mn_1/5Fe_1/5Co_1/5Ni_1/5)₃O₄ NFs calcined at 500 °C and results from the lower outer 3d‐electron number, e_g filling closer to its optimal value and higher occupation of 16d sites by the most redox‐active species.