Abstract: A switching device according to an embodiment includes a switching layer disposed between a first electrode and a second electrode. The switching layer contains a material containing a first cation element Z, Te, and N. This material contains at least 5 atomic % or more of each of Z, Te, and N, and when an atomic ratio of Te is X, an atomic ratio of N is Y, an atomic ratio of Z is W, a ratio of Z2Te3 to ZN on a straight line connecting a compound of the first cation element Z with tellurium and nitride of the first cation element Z in a ternary phase diagram of Z, Te, and N is A, and a change in an N content from the Z2Te3—ZN line is B, the material has a composition satisfying X=1.2 (1?A) (0.5+B), Y=A (0.5+B), and W=1?X?Y, where ?0.06?B?0.06 is satisfied when ?>A and ¾<A, and ?0.06?B and Y?0.45 are satisfied when ??A?¾.

Abstract: Provided are a catalyst ink for a fuel cell, which secures both the viscosity of the catalyst ink and the electricity generation performance of a fuel cell produced by using the catalyst ink, a catalyst layer for a fuel cell, and a membrane electrode assembly. The catalyst ink for a fuel cell may contain a catalyst-supporting support, an ionomer that is proton conductive, and cellulose-based nanofibers.

Abstract: Provided are a catalyst ink for a fuel cell, which secures both the viscosity of the catalyst ink and the electricity generation performance of a fuel cell produced by using the catalyst ink, a catalyst layer for a fuel cell, and a membrane electrode assembly. The catalyst ink for a fuel cell may contain a catalyst-supporting support, an ionomer that is proton conductive, and cellulose-based nanofibers.