Method for preparing palladium-loaded heterojunction composite framework aerogel and method for preparing hydrogen sensor

A method for preparing a palladium-loaded heterojunction composite framework aerogel, comprising:

• (1) preparing a hollow tin dioxide (SnO2) nanofiber;
• (2) grinding the hollow SnO2 nanofiber followed by addition of a tetrabutyl titanate-absolute ethanol mixture and stirring at room temperature to form a tetrabutyl titanate-hollow SnO2 nanofiber mixed solution;
• wherein a volume ratio of tetrabutyl titanate to absolute ethanol in the tetrabutyl titanate-absolute ethanol mixture is 1:(20-25);
• and a mass ratio of the hollow SnO2 nanofiber to the tetrabutyl titanate-absolute ethanol mixture is 1:(50-100);
• (3) preparing a palladium dichloride (PdCl2) precursor solution with a pH ranging from 1.9 to 4.7;
• (4) dropwise adding the PdCl2 precursor solution prepared in step (3) to the tetrabutyl titanate-hollow SnO2 nanofiber mixed solution prepared in step (2) at a rate of 1-2 drops/s under stirring at room temperature until a crude gel is formed;
• and subjecting the crude gel to aging and multiple solvent replacements with anhydrous ethanol to form a heterojunction double-network composite framework gel;
• and
• (5) placing the heterojunction double-network composite framework gel inside a supercritical drying kettle, followed by immersion in absolute ethanol, and adjusting a temperature and pressure in the supercritical drying kettle to allow carbon dioxide gas inside the supercritical drying kettle to reach a supercritical fluid state;
• regulating the pressure in the supercritical drying kettle such that a three-dimensional (3D) network structure of the heterojunction double-network composite framework gel is maintained in carbon dioxide gas;
• subjecting the heterojunction double-network composite framework gel to degassing and pressure holding to allow palladium ions to grow into palladium nanoparticles in situ, so as to form a palladium nanoparticle-loaded heterojunction double-network composite framework aerogel.