Improving the catalytic efficiency of platinum for the hydrogen evolution reaction is valuable for water splitting technologies. Hydrogen spillover has emerged as a new strategy in designing binary-component Pt/support electrocatalysts. However, such binary catalysts often suffer from a long reaction pathway, undesirable interfacial barrier, and complicated synthetic processes. Here we report a single-phase complex oxide La2Sr2PtO7+δ as a high-performance hydrogen evolution electrocatalyst in acidic media utilizing an atomic-scale hydrogen spillover effect between multifunctional catalytic sites. With insights from comprehensive experiments and theoretical calculations, the overall hydrogen evolution pathway proceeds along three steps: fast proton adsorption on O site, facile hydrogen migration from O site to Pt site via thermoneutral La-Pt bridge site serving as the mediator, and favorable H2 desorption on Pt site. Benefiting from this catalytic process, the resulting La2Sr2PtO7+δ exhibits a low overpotential of 13 mV at 10 mA cm−2, a small Tafel slope of 22 mV dec−1, an enhanced intrinsic activity, and a greater durability than commercial Pt black catalyst.

With the increasing occurrence of vascular diseases and poor long-term patency rates of current small diameter vascular grafts, it becomes urgent to pursuit biomaterial as scaffold to mimic blood vessel morphologically and mechanically. In this study, novel human-like collagen (HLC, produced by recombinant E. coli)/chitosan tubular scaffolds were fabricated by cross-linking and freeze-drying process. The scaffolds were characterized by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and tensile test, respectively. Human venous fibroblasts were expanded and seeded onto the scaffolds in the density of 1 x 10(5) cells/cm(2). After a 15-day culture under static conditions, the cell-polymer constructs were observed using SEM, confocal laser scanning microscopy (CLSM), histological examination, and biochemical assays for cell proliferation and extracellular matrix production (collagen and glycosaminoglycans). Furthermore, the scaffolds were implanted into rabbits' livers to evaluate their biocompatibility. The results indicated that HLC/chitosan tubular scaffolds (1) exhibited interconnected porous structure; (2) achieved the desirable levels of pliability (elastic up to 30% strain) and stress of 300 +/- 16 kPa; (3) were capable of enhancing cell adhesion and proliferation and ECM secretion; (4) showed superior biocompatibility. This study suggested the feasibility of HLC/chitosan composite as a promising candidate scaffold for blood vessel tissue engineering.

The biodegradability, histocompatibility and biocompatibility of injectable HCD hydrogels were determined throughin vitroandin vivotests.

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