Abstract: A method of preparing metal particle dispersion includes preparing an ion-containing solution that contains metal ions (step S11), performing heat treatment on a protectant having an average molecular weight of greater than or equal to 5000 and less than or equal to 32500 (step S12), and mixing the aforementioned ion-containing solution, a reducing agent, and the protectant subjected to the heat treatment in step S12 to prepare metal particle dispersion in which metal microparticles are dispersed by a liquid-phase reduction method (step S13). This method achieves improved dispersibility and further fragmentation of the metal microparticles in the metal particle dispersion.

Abstract: A hydrogen production method and hydrogen production system using the reaction of water and aluminum, the hydrogen production method and system being capable of continuously generating hydrogen for a long period of time without causing a decrease in the total amount of hydrogen generation. A hydrogen generation system according to one embodiment of the present invention includes aluminum sheet placed in a container and calcium hydroxide contained in the same container. In the hydrogen production system having the previously described configuration, water is poured in the container to dissolve the calcium hydroxide so that an aqueous solution is prepared, and the aluminum sheet is immersed in this aqueous solution. As a result, the hydrogen generation reaction begins, generating hydrogen gas. The amount, rate and duration of the generation of hydrogen gas can be controlled by adjusting the area and thickness of the aluminum sheet.