A self-supported mixed metal sulfide catalyst: (a) comprising molybdenum sulfide, nickel sulfide, and tungsten sulfide, and wherein the catalyst is characterized as having molar ratios of metal components Ni:Mo:W in a region defined by six points ABCDEF of a ternary phase diagram, and wherein the six points ABCDEF are defined as: A in which Ni=0.67, Mo=0.00, W=0.33; B in which Ni=0.67, Mo=0.10, W=0.23; C in which Ni=0.60, Mo=0.15, W=0.25; D in which Ni=0.52, Mo=0.15, W=0.33; E in which Ni=0.52, Mo=0.06, W=0.42; F in which Ni=0.58, Mo=0.0, W=0.42; or (b) comprising molybdenum sulfide, nickel sulfide, and tungsten sulfide, wherein the catalyst is characterized as having a multi-phased structure comprising five phases: a molybdenum sulfide phase, a tungsten sulfide phase, a molybdenum tungsten sulfide phase, an active nickel phase, and a nickel sulfide phase, wherein the catalyst is characterized as having molar ratios of metal components Ni:Mo:W in a region defined by five points ABCDE of a ternary phase diagram, and wherein the five points ABCDE are defined as: A in which Ni=0.72, Mo=0.00, W=0.28; B in which Ni=0.25, Mo=0.00, W=0.75; C in which Ni=0.25, Mo=0.25, W=0.50; D in which Ni=0.60, Mo=0.25, W=0.15; E in which Ni=0.72, Mo=0.13, W=0.15, wherein the active nickel phase comprises: a) at least one of atomic nickel and reduced nickel substituted into the edge of molybdenum tungsten sulfide phase for a tri-metallic catalyst or tungsten sulfide phase for a bi-metallic Ni:W catalyst, and b) NiS x nanoparticles, where 0 ≤ x ≤ 1, dispersed onto the molybdenum tungsten sulfide phase or decorating the edge of the molybdenum tungsten sulfide phase for a tri-metallic catalyst or tungsten sulfide phase for a bi-metallic Ni:W catalyst. (a) comprising molybdenum sulfide, nickel sulfide, and tungsten sulfide, and wherein the catalyst is characterized as having molar ratios of metal components Ni:Mo:W in a region defined by six points ABCDEF of a ternary phase diagram, and wherein the six points ABCDEF are defined as: A in which Ni=0.67, Mo=0.00, W=0.33; B in which Ni=0.67, Mo=0.10, W=0.23; C in which Ni=0.60, Mo=0.15, W=0.25; D in which Ni=0.52, Mo=0.15, W=0.33; E in which Ni=0.52, Mo=0.06, W=0.42; F in which Ni=0.58, Mo=0.0, W=0.42; or (b) comprising molybdenum sulfide, nickel sulfide, and tungsten sulfide, wherein the catalyst is characterized as having a multi-phased structure comprising five phases: a molybdenum sulfide phase, a tungsten sulfide phase, a molybdenum tungsten sulfide phase, an active nickel phase, and a nickel sulfide phase, wherein the catalyst is characterized as having molar ratios of metal components Ni:Mo:W in a region defined by five points ABCDE of a ternary phase diagram, and wherein the five points ABCDE are defined as: A in which Ni=0.72, Mo=0.00, W=0.28; B in which Ni=0.25, Mo=0.00, W=0.75; C in which Ni=0.25, Mo=0.25, W=0.50; D in which Ni=0.60, Mo=0.25, W=0.15; E in which Ni=0.72, Mo=0.13, W=0.15, wherein the active nickel phase comprises: a) at least one of atomic nickel and reduced nickel substituted into the edge of molybdenum tungsten sulfide phase for a tri-metallic catalyst or tungsten sulfide phase for a bi-metallic Ni:W catalyst, and b) NiS x nanoparticles, where 0 ≤ x ≤ 1, dispersed onto the molybdenum tungsten sulfide phase or decorating the edge of the molybdenum tungsten sulfide phase for a tri-metallic catalyst or tungsten sulfide phase for a bi-metallic Ni:W catalyst.