1 . A porous body comprising a framework having a three-dimensional network structure,
the framework having a body including nickel and cobalt as constituent elements, the body of the framework including the cobalt at a proportion in mass of 0.2 or more and 0.8 or less relative to a total mass of the nickel and the cobalt.
2 . The porous body according to claim 1 , wherein the body of the framework includes the cobalt at a proportion in mass exceeding 0.4 and less than 0.6 relative to the total mass of the nickel and the cobalt.
3 . The porous body according to claim 1 , wherein the body of the framework further includes at least one non-metallic element selected from the group consisting of nitrogen, sulfur, fluorine, and chlorine as a constituent element, and the non-metallic element is contained at a proportion of 5 ppm or more and 10,000 ppm or less in total with respect to the body of the framework.
4 . The porous body according to claim 1 , wherein the body of the framework further includes phosphorus as a constituent element, and the phosphorus is contained at a proportion of 5 ppm or more and 50,000 ppm or less with respect to the body of the framework.
5 . The porous body according to claim 1 , wherein the body of the framework further includes at least two non-metallic elements selected from the group consisting of nitrogen, sulfur, fluorine, chlorine and phosphorus as constituent elements, and the non-metallic elements are contained at a proportion of 5 ppm or more and 50,000 ppm or less in total with respect to the body of the framework.
6 . The porous body according to claim 1 , wherein the body of the framework further includes oxygen as a constituent element.
7 . The porous body according to claim 6 , wherein the oxygen is included in the body of the framework in an amount of 0.1% by mass or more and 35% by mass or less.
8 . The porous body according to claim 6 , wherein the body of the framework includes a spinel-type oxide.
9 . The porous body according to claim 1 , wherein when the body of the framework is observed in cross section at a magnification of 3,000 times to obtain an observed image the observed image presents in any area 10 μm square thereof five or less voids each having a longer diameter of 1 μm or more.
10 . The porous body according to claim 1 , wherein the framework is hollow.
11 . The porous body according to claim 1 , having a sheet-shaped external appearance and a thickness of 0.2 mm or more and 2 mm or less.
12 . A fuel cell comprising a current collector for an air electrode and a current collector for a hydrogen electrode, at least one of the current collector for the air electrode or the current collector for the hydrogen electrode including the porous body according to claim 1 .
13 . A steam electrolysis apparatus comprising a current collector for an air electrode and a current collector for a hydrogen electrode, at least one of the current collector for the air electrode or the current collector for the hydrogen electrode including the porous body according to claim 1 .