摘要：尖晶石相ZnCr_(2)O_(4)作为CO/CO_(2)加氢反应的重要催化材料,其表面活性氢物种的产生机制及其对CO加氢反应的作用一直备受争议。首先计算了最稳定的ZnCr_(2)O_(4)(111)表面H_(2)物种的活化,结果表明H_(2)分子在ZnCr_(2)O_(4)(111)表面异裂解离产生的Zn-H和O-H物种比H_(2)均裂解离产生两个O-H物种更加容易,且H_(2)通过异裂解离可以有效产生高活性的Zn-H物种,这主要归因于ZnCr_(2)O_(4)(111)表面Zn物种具有灵活的3d轨道,同时由于Zn 3d轨道具有较高的对称性,因此有利于H负物种的稳定。最后,研究了ZnCr_(2)O_(4)表面CO选择性加氢的反应机制,发现ZnH物种进攻CO分子的C~(δ+)/O~(δ-)生成COH或HCO物种能垒均比O-H物种作为氢源产生相同的关键中间物种能垒更低,说明Zn-H物种是CO选择性加氢反应具有高活性的关键物种;其次,还可以发现Zn-H物种活化CO产生HCO物种能垒最低,表明Zn-H物种对CO选择性加氢反应也体现出较高的活性。实验结果可为Zn基合成气选择性加氢催化材料的理性设计提供一些指导。

摘要：Molybdenum disulfide（MoS2） has attracted extensive attention as an alternative to replace noble electrocatalysts in the hydrogen evolution reaction（HER）. Here, we highlight an efficient and straightforward ball milling method,using nanoscale Cu powders as reductant to reduce MoS2 engineering S-vacancies into MoS2 surfaces, to fabricate a defectrich MoS2material（DR-MoS2）. The micron-sized DR-MoS2 catalysts exhibit significantly enhanced catalytic activity for HER with an overpotential（at 10 mA cm^-2） of 176 m V in acidic media and 189 m V in basic media, surpassing most of Mo-based catalysts previously reported, especially in basic solution. Meanwhile stability tests confirm the outstanding durability of DR-MoS2 catalysts in both acid and basic electrolytes. This work not only opens a new pathway to implant defects to MoS2, but also provides low-cost alternative for efficient electrocatalytic production of hydrogen in both alkaline and acidic environments.

摘要：Oxygen electrocatalysis,exemplified by the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),is central to energy storage and conversion technologies such as fuel cells,metal-air batteries,and water ***,highly effective and inexpensive earth-abundant materials are sought after to replace the noble metal-based electrocatalysts currently in ***,metal-organic frameworks(MOFs)and carbon-based MOF derivatives have attracted considerable attention as efficient catalysts due to their exceedingly tunable morphologies,structures,compositions,and ***,we report two-dimensional(2D)MOF/MOF derivative coupled arrays on nickel foam as binder-free bifunctional ORR/OER catalysts with enhanced electrocatalytic activity and *** remarkable electrochemical properties are primarily attributed to fully exposed active sites and facilitated charge-transfer *** coupled and hierarchical nanosheet arrays produced via our growth-pyrolysis-regrowth strategy offer promise in the development of highly active electrodes for energy-related electrochemical devices.