The present disclosure is to provide a multi-junction light energy conversion element including a material having a band gap suitable for a light energy conversion layer located upstream in an incidence direction of light. The present disclosure provides a light energy conversion element, comprising a first light energy conversion layer containing SrZn.sub.2N.sub.2 and a second light energy conversion layer containing an light energy conversion material. The light energy conversion material has a narrower band gap than the SrZn.sub.2N.sub.2.

The present disclosure relates to power plants. The teachings thereof may be embodied in processes for producing ammonia and energy, e.g., a method for producing ammonia and energy comprising: spraying or atomizing an electropositive metal; burning the metal with a reaction gas; mixing the reacted mixture with water; separating the mixture into (a) solid and liquid constituents and (b) gaseous constituents; at least partially converting energy of the solid and liquid constituents and of the gaseous constituents; and separating ammonia from the gaseous constituents. Mixing the reacted mixture may include spraying or atomizing the water or the aqueous solution or the suspension of the hydroxide of the electropositive metal into the reacted mixture.

A catalyst is provided which is used for continuously synthesizing ammonia using a gas containing hydrogen and nitrogen as a raw material, wherein a transition metal which exhibits catalytic activity is supported by a support, and the support is a two-dimensional electride or a precursor thereof. The two-dimensional electride or the precursor thereof is a metal nitride represented by MxNyHz (M represents one or two or more of Group II metals selected from the group consisting of Mg, Ca, Sr and Ba, and x, y and z are in ranges of 1x11, 1y8, and 0z4 respectively, in which x is an integer, and y and z are not limited to an integer) or M.sub.3N.sub.2 (M is the same as above), or a metal carbide selected from the group consisting of Y.sub.2C, Sc.sub.2C, Gd.sub.2C, Tb.sub.2C, Dy.sub.2C, Ho.sub.2C and Er.sub.2C. These catalysts are used for continuously reacting nitrogen with hydrogen, which are raw materials, on the catalyst, wherein the reaction is performed in an ammonia synthesis reaction system under the preferable conditions of a reaction temperature which is equal to or higher than 100 C. and equal to or lower than 600 C., and a reaction pressure which is equal to or higher than 10 kPa and lower than 20 MPa.