Highly efficient decomposition of ammonia using high-entropy alloy catalysts

Abstract

Ammonia represents a promising liquid fuel for hydrogen storage, but its large-scale application is limited by the need for precious metal ruthenium (Ru) as catalyst. Here we report on highly efficient ammonia decomposition using novel high-entropy alloy (HEA) catalysts made of earth abundant elements. Quinary CoMoFeNiCu nanoparticles are synthesized in a single solid-solution phase with robust control over the Co/Mo atomic ratio, including those ratios considered to be immiscible according to the Co-Mo bimetallic phase diagram. These HEA nanoparticles demonstrate substantially enhanced catalytic activity and stability for ammonia decomposition, with improvement factors achieving >20 versus Ru catalysts. Catalytic activity of HEA nanoparticles is robustly tunable by varying the Co/Mo ratio, allowing for the optimization of surface property to maximize the reactivity under different reaction conditions. Our work highlights the great potential of HEAs for catalyzing chemical transformation and energy conversion reactions.

Computationally aided, entropy-driven synthesis of highly efficient and durable multi-elemental alloy catalysts

“…In addition, despite the same composition, the Ru-5 MEA-NPs obviously outperformed the Ru-5 IMPs sample, indicating that the improved performance mostly comes from the alloy structure rather than the simple element blending. Figure 5B shows that the conversion efficiency of RuRhCoNi-MEA is much higher compared with the simple addition of Ru + RhCoNi, indicating a strong synergistic effect in the RuRhCoNi MEA sample that leads to enhanced performances (7,35). The substantial increase in the catalytic performance of both MEA-NPs demonstrates the advantage of using multi-elemental composition in an alloy structure for the discovery of high-performance catalysts.…”

High‐Temperature Shock Enabled Nanomanufacturing for Energy‐Related Applications

“…Reproduced with permission. [ 14 ] Copyright 2019, Springer Nature. d) Spectral radiance measurement of the same sample with different electrical power inputs.…”

“…[ 21 ] Moreover, the rapid HTS method can also be employed to prepare monophasic nanoparticles by melting chemical reaction of raw elements and accurate control of precursors. Currently, various nanomaterials have been successfully prepared via the HTS process, including monometallic and semiconductor nanoparticles (e.g., Si, Sn, Al, Au, Pd, Ru, Ir, Pt, Ni, and Ag), [ 12,17,18,22 ] compound nanoparticles (e.g., SiC, FeS 2 , CoS, Co 2 B, Co 3 O 4 , MoS 2 , and CoFeP x ), [ 19b,23 ] bimetallic alloy (e.g., NiFe, PdNi, PtFe, and Cu 0.9 Ni 0.1 ), [ 19a,21b,24 ] mixing entropy nanoparticles (e.g., CoMoFeNiCu, PtPdRhRuCe, and PtPdCoNiFeCuAuSn), [ 10a,14 ] and single atoms (e.g., Pt, Ru, and Co). [ 25 ]…”

“…In 2019, Xie et al applied the HTS technique to fabricate a novel HEA composed of Co, Mo, Fe, Ni, and Cu ( Figure 9 ). [ 14 ] The HTS method helps to overcome the immiscibility from the Co–Mo bimetallic phase diagram and fabricated the single‐phase CoMoFeNiCu nanoparticles. Note that the HEA nanoparticles shows better catalytic activity and stability for NH 3 decomposition, as compared with conventional bimetallic Co–Mo and monometallic Ru catalysts.…”

Fast Site-to-site Electron Transfer of High-entropy Alloy Nanocatalyst Driving Redox Electrocatalysis

“…[23][24][25] Recently, some HEAs had used as catalysts for electrocatalytic reactions, which display superior stability and catalytic selectivity and activity compared with traditional alloys. 13,[26][27][28][29][30] However, the traditional method mainly produce bulk HEAs rather than nanostructures. 26,[31][32][33][34] Moreover, the preparation of uniform nanostructured HEAs with small size (< 10 nm) currently requires speci c equipment (fast heating/cooling rate, ~10 5 K per second), high temperature (~2000 kelvin), and high temperature resistant and conductive substrate (carbon nano ber), such as carbon-thermal shock method.…”