Highly active layered double hydroxide-derived cobalt nano-catalysts for p-nitrophenol reduction
Highly active layered double hydroxide-derived cobalt nano-catalysts for p-nitrophenol reduction
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DOI：
10.1016/j.apcatb.2015.06.052
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发表时间：
2016-01-01
影响因子：
22.1
通讯作者：
Na, Chongzheng
中科院分区：
文献类型：
--
作者：
Ma, Hanyu;Wang, Haitao;Na, Chongzheng
用非贵金属催化剂取代贵金属催化剂是公认的降低催化水处理成本的策略。然而，这一战略的实施具有挑战性。为了通过使用非贵金属催化剂来降低成本，非贵金属催化剂和贵金属催化剂之间的反应性比必须超过它们的价格比。本文首次报道了在硼氢化物催化还原对-硝基苯酚反应中，钴(Co)比最活跃的钯贵金属催化剂的比价条件被超越。这是通过钴-镁-铝层状双氢氧化物前驱体的热相变将钴纳米颗粒附着在二维层状双氧化物(LDO)纳米盘上实现的。结果表明，LDO-Co的催化活性是金属阳离子中Co摩尔分数的函数。当催化剂的摩尔分数为28%，催化剂用量为1g L-1(AS Co)，初始对硝基苯酚浓度为0.2 mM时，在25℃下的准一级反应速率常数为86(+/-3)min(-1)。与文献中描述的其他钴纳米催化剂相比，LDO-Co设计至少将钴的反应活性提高了49倍。我们进一步表明，LDO-Co的高反应活性在反复重复使用后以及用适中的还原剂和氢给体甲酸盐取代硼氢化物后仍然保持。我们认为，LDO-Co的高活性和优异的寿命是由于钴通过类似于尖晶石钴氧化物的钴-氧键在LDO上的异质外延固定的结果。(C)2015爱思唯尔B.V.保留所有权利。
Replacing precious noble-metal catalysts with non-precious metal ones is a well-recognized strategy for reducing the cost of catalytic water treatment. The implementation of this strategy is, however, challenging. To reduce the cost by using non-precious metal catalysts, the reactivity ratio between non-precious and precious metal catalysts must exceed their price ratio. Here, we report for the first time that the parity condition has been surpassed for cobalt (Co), in comparison to the most active precious metal catalyst made of palladium, in the catalytic reduction of p-nitrophenol with borohydride. This is achieved by affixing Co nanoparticles on two-dimensional layered double oxide (LDO) nano disks through thermal phase transformation of cobalt-magnesium-aluminum layered double hydroxide precursors. We show that the catalytic activity of LDO-Co is a function of Co molar fraction among metal cations. The highest reactivity is achieved at a molar fraction of 28%, giving a pseudo first order rate constant of 86(+/- 3) min(-1) at 25 degrees C for a catalyst dose of 1 g L-1 (as Co) and an initial p-nitrophenol concentration of 0.2 mM. Compared to other Co nano-catalysts described in the literature, the LDO-Co design has improved the reactivity of cobalt by at least 49 times. We further show that the high reactivity of LDO-Co remains after repeated reuse as well as after borohydride is replaced by formate, a moderate reductant and hydrogen donor. We propose that the high reactivity and superior longevity of LDO-Co are results of the heteroepitaxial fixation of cobalt on LDO through cobalt-oxygen bonds that are similar to those in spinel cobalt oxide. (C) 2015 Elsevier B.V. All rights reserved.