Abstract: Novel intercalation electrode materials including ternary acetylides of chemical formula: AnMC2 where A is alkali or alkaline-earth element; M is transition metal or metalloid element; C2 is reference to the acetylide ion; n is an integer that is 0, 1, 2, 3 or 4 when A is alkali element and 0, 1, or 2 when A is alkaline-earth element. The alkali elements are Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs) and Francium (Fr). The alkaline-earth elements are Berilium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), and Radium (Ra). M is a transition metal that is any element in groups 3 through 12 inclusive on the Periodic Table of Elements (elements 21 (Sc) to element 30 (Zn)). In another exemplary embodiment, M is a metalloid element.

Abstract: A low-workfunction photocathode includes a photoemissive material employed as a coating on the photocathode. The photoemissive material includes AnMC2, where A is a first metal element, the first element is an alkali metal, an alkali-earth element or the element Al; n is an integer that is 0, 1, 2, 3 or 4; M is a second metal element, the second metal element is a transition metal or a metal stand-in; and C2 is the acetylide ion C22?. The photoemissive material includes a crystalline structure or non-crystalline structure of rod-like or curvy 1-dimensional polymeric substructures with MC2 repeating units embedded in a matrix of A.