RESUMO
Hydrogen is regarded as one of the most promising clean substitutes for fossil fuels toward a carbon-zero society. However, the safety management of the upcoming hydrogen energy infrastructure has not been fully prepared, in contrast to the well-established natural gas and gasoline systems. On the frontline is the guard post of hydrogen detectors, which need to be deployed on various structural surfaces and environmental conditions. Conventional hydrogen detectors are usually bulky and environmentally sensitive, limiting their flexible and conformal deployment to various locations, such as pipelines and valves. Herein, we demonstrate the successful synthesis of a palladium-modified epitaxial metal-organic framework (MOF) on single-layer graphene to fabricate a heterostructure material (Epi-MOF-Pd). Device based on the heterostructure demonstrates high sensitivity toward low- concentration H2 (155% resistance response to 1% H2 within 12 s, a theoretical detection limit of 3 ppm). The 25 nm epitaxial MOF acquires electrons from the Pd nanoparticles after the trace amount of H2 is chemically adsorbed and further relays the electrons to the highly conductive graphene. The Epi-MOF-Pd is both flexible and enduring, and maintains stable detection over 10 000 bending cycles. Through photolithography, device arrays with a density of 3000 units/cm2 are successfully fabricated. This versatile material provides a prospective avenue for the mass production of high-performance chemical-sensitive electronics, which could significantly improve the hydrogen safety management on demand.
RESUMO
Increasing photoactive areas and oxygen vacancy to improve the separation and utilization of electrons and holes in a photocatalytic process are a guarantee for highly photocatalysis efficiency. In this work, we report a CAs@B-TiO2core-shell nanospheres via a nanoscale water spray assisted method to deposit of black titanium dioxide (B-TiO2) on carbon aerogel sphere (CAs) though slowly hydrolyzing of butyl titanate (e.g. TBOT) in an ethanol-water system. On this basis, furthermore, a facile one-step N2H4 · H2O treatment was used to introduces oxygen vacancies on the surface of TiO2coating layer forming black TiO2. Oxygen vacancies can extend the optical response range of the TiO2shell from the ultraviolet to the visible region, and increase conductivity and charge transport on the interface of core-shell structure. This study reveals the importance of surface oxygen vacancies for reducing band gaps and developing highly active photocatalysts under visible light.
