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Abstract A crucial step toward clean hydrogen (H2) energy production through water electrolysis is to develop high‐stability catalysts, which can be reliably used at high current densities for a long time. So far, platinum group metals (PGM) and their oxides, for example, Pt and iridium oxide (IrO2) have been well‐regarded as the criterion for hydrogen and oxygen evolution reactions (HER and OER) electrocatalysts. However, the PGM catalysts usually undergo severe performance decay during the long‐term operation. Herein, the in situ growth of iron phosphosulfate (Fe2P2S6) nanocrystals (NCs) catalysts on carbon paper synthesized by combing chemical vapor deposition with solvent‐thermal treatment is reported to show competitive performance and stability as compared to the state‐of‐the‐art PGM catalysts in a real water electrolyzer. A current density of 370 mA cm−2is achieved at 1.8 V when using Fe2P2S6NCs as bifunctional catalysts in an anion exchange membrane water electrolyzer. The Fe2P2S6NCs also show much better stability than the Pt‐IrO2catalysts at 300 mA cm−2for a continuous 24 h test. The surface generated FeOOH on Fe2P2S6is the real active site for OER. These results indicate that the Fe2P2S6NCs potentially can be used to replace PGM catalysts for practical water electrolyzers.
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Bioresponsive Microneedles with a Sheath Structure for H 2 O 2 and pH Cascade‐Triggered Insulin Delivery
Abstract Self‐regulating glucose‐responsive insulin delivery systems have great potential to improve clinical outcomes and quality of life among patients with diabetes. Herein, an H2O2‐labile and positively charged amphiphilic diblock copolymer is synthesized, which is subsequently used to form nano‐sized complex micelles (NCs) with insulin and glucose oxidase of pH‐tunable negative charges. Both NCs are loaded into the crosslinked core of a microneedle array patch for transcutaneous delivery. The microneedle core is additionally coated with a thin sheath structure embedding H2O2‐scavenging enzyme to mitigate the injury of H2O2toward normal tissues. The resulting microneedle patch can release insulin with rapid responsiveness under hyperglycemic conditions owing to an oxidative and acidic environment because of glucose oxidation, and can therefore effectively regulate blood glucose levels within a normal range on a chemically induced type 1 diabetic mouse model with enhanced biocompatibility.
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- Award ID(s):
- 1708620
- PAR ID:
- 10053658
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Small
- Volume:
- 14
- Issue:
- 14
- ISSN:
- 1613-6810
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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