A new study conducted by Chinese scientists reported Hard-Sphere Random Close-Packed Au47Cd2(TBBT)31 Nanoclusters with a Faradaic Efficiency of Up to 96% for Electrocatalytic CO2 Reduction to CO.
This work was done by Professer WU Zhikun's group at Institute of Solid State Physics (ISSP) under Hefei Institutes of Physical Science in collaboration with YANG Jun's group at Institute of process enigineering (IPE), Chinese Academy of Sciences.
"Anti-galvanic reduction (AGR)" is formally opposite to the classic "alvanic reaction" with a history of about 240 years. The unprecedented reaction was reported by WU in 2012.
Subsequently, WU's group conducted researches on mechanism and application (including application in ion recognition, synthesis, and so on) of anti-galvanic reaction, and made a series of progresses.
In the early stage, TIAN Shubo, et al. revealed that "AGR" depends on the ion precursor and ion dose, inspired by which, ZHUANG Shengli, et al. established the "two-phase AGR" method taking advantage of the high reaction activity of the surface and interface, and synthesized the Au47Cd2 clusters that cannot be obtained by the single-phase method (Fig. 1a, b), which provides a new routine for the accurate synthesis of alloy nanoclusters.
It is also interesting that this novel alloy cluster not only exhibits a special Hard-Sphere Random Close-Packed structure (Fig. 1b), but also shows a higher Faraday efficiency (96%, Fig. 1c) of electrocatalytical reduction of CO2 to CO. Its performance is better than not only the precursor clusters, but also most of the reported catalysts, and is among the list of highest electrocatalytic efficiency reported so far.
As we all know, cadmium is a heavy metal that endangers the environment. The introduction of cadmium into gold clusters through "two-phase AGR" can significantly improve the catalytic efficiency of the precursor clusters, and therefore turn bane into boon, having important implication for environmental improvement. The accurate compositions and structures of metal nanoclusters provide prerequisites for deep understandings of catalytical mechanisms.
Further theoretical calculation shows that the introduction of active metal Cd changes the adsorption configuration of intermediate product COOH* on the cluster surface (Fig. 1e), and changes the reaction kinetics (Fig. 1f), thus significantly improving the catalytic efficiency.
This work is supported by the National Natural Science Foundation of China, China Postdoctoral Science Foundation, Hefei Institute of material science, Chinese Academy of Sciences, Institute of solid state physics, and Institute of process engineering, Chinese Academy of Sciences.
a) Au44(TBBT)28; b) Au47Cd2(TBBT)31; c) CO Faradaic efficiency of the investigated catalystsath differently applied potentials; d) The partial current density of CO normalized by Au mass in the catalyst; e) the adsorption configuration of COOH* on Au47Cd2; f) Free energy diagram for electrocatalytic CO2 reduction to CO on Au47Cd2(TBBT)31, Au44(TBBT)28 and Au NPs. (Image by ZHUANG Shengli)
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