Grain boundaries bear many active sites for surface reactions (e.g. electrocatalysis and energy storage), and increasing the grain boundaries has become an important strategy to tune the number of surface active sites and the reaction kinetics. Herein, we show that a simple in situ electrochemical tuning method can be used to turn Co(OH)_x(CO₃)_0.5(2−x) crystals into interconnected ultrafine nanoparticles with enriched grain boundaries. The grain boundaries offer numerous unparalleled active sites for highly efficient electro-oxidation of hydrazine. The electrochemically-tuned Co(OH)_x(CO₃)_0.5(2−x) shows an onset potential (−1.12 V vs. Ag/AgCl) 180 mV smaller than that of the pristine Co(OH)_x(CO₃)_0.5(2−x), and delivers a high current density of 62.4 mA cm⁻² at −0.90 V vs. Ag/AgCl, which is 27 times higher than that of the pristine Co(OH)_x(CO₃)_0.5(2−x). This work produces the most active non-metallic catalyst for hydrazine oxidation with catalytic activity comparable to the state-of-the-art catalysts. Moreover, our electrochemical tuning method is applicable to other materials (e.g. Co₃O₄, Co(OH)₂ and Ni(OH)₂).

中文翻译：

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电化学调谐的碳酸钴氢氧化物具有丰富的晶界，可实现肼的高效电氧化†

晶界具有许多用于表面反应的活性位点（例如电催化和能量存储），增加晶界已成为调节表面活性位点数量和反应动力学的重要策略。在这里，我们表明，可以使用一种简单的原位电化学调谐方法将Co（OH）_x（CO ₃）_{0.5（2- x）}晶体转变为具有富集晶界的互连超细纳米颗粒。晶界提供了许多无与伦比的活性位点，用于肼的高效电氧化。电化学调谐的Co（OH）_x（CO ₃）_{0.5（2- x）}所示的起始电势（-1.12 V相对于银/氯化银）180毫伏比原始的Co（OH）的更小的_X（CO ₃） _{0.5（2- X）}，并提供的62.4毫安cm的高电流密度^-在相对于Ag / AgCl的-0.90 V下为²，比原始Co（OH） _x（CO ₃） _{0.5（2- x）}高27倍。这项工作生产了用于肼氧化的最具活性的非金属催化剂，其催化活性可与最新型催化剂相比。此外，我们的电化学调谐方法适用于其他材料（例如， Co ₃O ₄，Co（OH）₂和Ni（OH）₂）。