Single layer graphene encapsulating non-precious metals as high-performance electrocatalysts for water oxidation
Single layer graphene encapsulating non-precious metals as high-performance electrocatalysts for water oxidation
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单层石墨烯封装非贵金属作为高性能水氧化电催化剂
DOI：
10.1039/c5ee03316k
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发表时间：
2016-01-01
影响因子：
32.5
通讯作者：
Bao, Xinhe
中科院分区：
文献类型：
--
作者：
Cui, Xiaoju;Ren, Pengju;Bao, Xinhe
析氧反应(OER)被认为是水电解生产清洁氢能的关键半反应，在动力学上并不受欢迎，通常需要贵金属催化剂IrO2和RuO2来降低过电位。使用非贵金属代替贵金属催化剂进行OER的主要挑战是它们的效率低和稳定性差，这迫切需要新的概念和战略来解决这一问题。在这里，我们报道了一种通用的策略，即在介孔二氧化硅的受限通道中直接合成单层石墨烯，该单层石墨烯包裹着均匀的富含稀土的三维过渡金属纳米粒子，如Fe，Co，Ni及其合金。石墨烯壳层的单原子厚度极大地促进了电子从被包裹的金属向石墨烯表面的转移，从而有效地优化了石墨烯表面的电子结构，从而触发了惰性石墨烯表面的OER活性。我们研究了单层石墨烯包裹的一系列非贵金属3d金属，发现包裹的FeNi合金在碱性溶液中表现出最好的过电流变活性，在10 mA cm−2时只有2 80 mV的过电位，并且在10 000循环后也具有很高的耐久性。非贵金属催化剂的活性和耐久性甚至超过了商用IrO2催化剂，显示出在OER中取代贵金属催化剂的巨大潜力。
The oxygen evolution reaction (OER) is recognized as a key half-reaction in water electrolysis for clean hydrogen energy, which is kinetically not favored and usually requires precious metal catalysts such as IrO2 and RuO2 to reduce the overpotential. The major challenge in using non-precious metals in place of these precious metal catalysts for OER is their low efficiency and poor stability, which urgently demand new concepts and strategies to tackle this issue. Herein, we report a universal strategy to directly synthesize single layer graphene encapsulating uniform earth-abundant 3d transition-metal nanoparticles such as Fe, Co, Ni and their alloys in a confined channel of mesoporous silica. The single atomic thickness of the graphene shell immensely promotes the electron transfer from the encapsulated metals to the graphene surface, which efficiently optimizes the electronic structure of the graphene surface and thereby triggers the OER activity of the inert graphene surface. We investigated a series of non-precious 3d metals encapsulated within single layer graphene, and found that the encapsulated FeNi alloy showed the best OER activity in alkaline solutions with only 280 mV overpotential at 10 mA cm−2, and also possessed a high durability after 10 000 cycles. Both the activity and durability of the non-precious catalyst even exceed that of the commercial IrO2 catalyst, showing great potential to replace precious metal catalysts in the OER.