Water‐stable metal halide perovskites could foster tremendous progresses in several research fields where their superior optical properties can make differences. In this work we report clear evidence of water stability in a lead‐free metal halide perovskite, namely DMASnBr3, obtained by means of diffraction, optical and X‐ray photoelectron spectroscopy. Such unprecedented water‐stability has been applied to promote photocatalysis in aqueous medium, in particular by devising a novel composite material by coupling DMASnBr3 to g‐C3N4, taking advantage from the combination of their optimal photophysical properties. The prepared composites provide an impressive hydrogen evolution rate >1700 μmol g−1 h−1 generated by the synergistic activity of the two composite costituents. DFT calculations provide insight into this enhancement deriving it from the favorable alignment of interfacial energy levels of DMASnBr3 and g‐C3N4. The demonstration of an efficient photocatalytic activity for a composite based on lead‐free metal halide perovskite in water paves the way to a new class of light‐driven catalysts working in aqueous environments.
We report on the N-decoration of multiwalled carbon nanotubes (MWCNTs) via chemical functionalization under mild reaction conditions. The introduction of tailored pyridinic functionalities as N-containing edge-type group mimics generates effective catalysts for the oxygen reduction reaction (ORR) in an alkaline environment. The adopted methodology lists a number of remarkable technical advantages, among which is an easy tuning of the electronic properties of N-containing groups. The latter aspect further increases the level of complexity for the rationalization of the role of the N-functionalities on the ultimate electrochemical performance of the as-prepared metal-free catalysts. Electrochemical outcomes crossed with the computed electronic charge density distributions on each scrutinized pyridine group have evidenced the central role played by the N-chemical environment on the final catalyst performance. Notably, small variations of the atomic charges on the N-proximal carbon atoms of the chemically grafted heterocycles change the overpotential values at which the oxygen reduction reaction starts. The protocol described hereafter offers an excellent basis for the development of more active metal-free electrocatalysts for the ORR. Finally, the asprepared catalytically active materials represent a unique model for the in-depth understanding of the underlying ORR mechanism.
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