Organic−inorganic hybrid perovskite materials have had remarkable success in photovoltaics due to their superior optoelectronic properties and compositional abundance. Most advances focus on the improvement of the heterojunction, in which nonperovskite materials are employed at the pertaining interfaces. Herein we demonstrate the modification of perovskite absorber by incorporation of CsPbBr 3 nanocrystals, which is congeneric to the absorber in terms of crystal structure and stoichiometry. It led to significant enhancement in photovoltaic performance in the corresponding devices, which was mainly attributed to the improved carrier dynamics over the resultant heterojunction. Therefore, a different strategy is suggested for further improvement of the perovskite heterojunction by using congeneric materials.

Pt-based alloy nanocrystals have shown great success in oxygen reduction electrocatalysis owing to their unique surface and electronic structures. However, they suffer from severe stability issues due to the dissolution of non-noble metal elements, leading to the "trade-off " between activity and stability. In this work, targeting the stability issue of a Pt x Cu y -based alloy, Pt 2 CuW 0.25 ternary alloy nanoparticles are synthesized by thermal reduction strategy based on wet-chemical method using W(CO) 6 as a reductant. Apart from the competitive activity, the obtained Pt 2 CuW 0.25 /C shows remarkable stability, whereby the area specific activity and mass activity maintain 89.5% and 95.9% of the initial values, respectively, after 30 000 cycles of accelerated polarization between 0.6 and 1.1 V (vs reversible hydrogen electrode). By using vacancy formation energy of surface Pt as the descriptor, it is found that the enhanced stability of Pt 2 CuW 0.25 /C originates mainly from the stronger bonding between W and Pt/Cu atoms, acting as an "adhesive" to stabilize the atoms from dissolution, which is further verified by chemical stability experiments. This work demonstrates a rational design strategy for ternary alloy nano-electrocatalyst that has high thermodynamic stability while maintaining high activity by employing high-melting-point metal.

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BackgroundThe VP1 protein of duck hepatitis A virus (DHAV) is a major structural protein that induces neutralizing antibodies in ducks; however, B-cell epitopes on the VP1 protein of duck hepatitis A genotype 1 virus (DHAV-1) have not been characterized.Methods and ResultsTo characterize B-cell epitopes on VP1, we used the monoclonal antibody (mAb) 2D10 against Escherichia coli-expressed VP1 of DHAV-1. In vitro, mAb 2D10 neutralized DHAV-1 virus. By using an array of overlapping 12-mer peptides, we found that mAb 2D10 recognized phages displaying peptides with the consensus motif LPAPTS. Sequence alignment showed that the epitope 173LPAPTS178 is highly conserved among the DHAV-1 genotypes. Moreover, the six amino acid peptide LPAPTS was proven to be the minimal unit of the epitope with maximal binding activity to mAb 2D10. DHAV-1–positive duck serum reacted with the epitope in dot blotting assay, revealing the importance of the six amino acids of the epitope for antibody-epitope binding. Competitive inhibition assays of mAb 2D10 binding to synthetic LPAPTS peptides and truncated VP1 protein fragments, detected by Western blotting, also verify that LPAPTS was the VP1 epitope.Conclusions and SignificanceWe identified LPAPTS as a VP1-specific linear B-cell epitope recognized by the neutralizing mAb 2D10. Our findings have potential applications in the development of diagnostic techniques and epitope-based marker vaccines against DHAV-1.

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