摘要
Hydrogen evolution in the presence of atmospheric level of oxygen is a significant barrier in the quest for an alternative,sustainable and green source of energy to counter the depleting fossil fuel sources and increasing global warming due to fossil fuel burning.Oxygen reduction is thermodynamically more favourable than proton reduction and it often produces reactive oxygenated species upon partial reduction which deactivates the catalyst.Thus,catalyst development is required for efficient proton reduction in the presence of oxygen.Here,we demonstrate an iron porphyrin having triazole containing 2nd sphere hydrogen bonding residues appended with redox active ferrocene moieties(α4-Tetra-2-(3-ferrocenyl-1,2,3-triazolyl)phenylporphyrin(FeFc4))as a bifunctional catalyst for fast and selective oxygen reduction to water and thus,preventing the proton reduction by the same catalyst from oxidative stress.Fe(0)is the active species for proton reduction in these iron porphyrin class of complexes and it is observed that the kinetics of proton reduction at Fe(0)state occurs at much faster rate than O2 reduction and thus,paving the way for selective proton reduction in the presence of oxygen.
采用洁净、可持续的替代能源以解决化石燃料的过度消耗及因其燃烧而导致的日益加剧的全球变暖问题已经成为当务之急.其中,如何实现在大气含氧条件下的析氢反应成为需要攻克的重大挑战.氧还原在热力学上比质子还原更容易进行,并且氧气部分还原时通常产生活性氧物种,致使催化剂失活.因此,需要开发在氧气存在情况下能够有效还原质子的催化剂.本文设计了一种四苯基铁卟啉分子,该分子通过三氮唑将四个二茂铁连接在苯基邻位,并证明该催化剂能够在有氧气的情况下高效还原质子,产生氢气.作为铁卟啉类化合物催化质子还原的活性物种,Fe(0)发生质子还原比发生O2还原的动力学速率快得多,从而为氧气存在下的选择性质子还原奠定了基础.
