A structurally versatile nickel phosphite acting as a robust bifunctional electrocatalyst for overall water splitting†,Energy & Environmental Science

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A structurally versatile nickel phosphite acting as a robust bifunctional electrocatalyst for overall water splitting†
Energy & Environmental Science ( IF 32.4 ) Pub Date : 2018-03-08 00:00:00 , DOI: 10.1039/c7ee03619a
Prashanth W. Menezes _{1,

2,

3} , Chakadola Panda _{1,

2,

3} , Stefan Loos _{3,

4,

5} , Florian Bunschei-Bruns _{1,

2,

3} , Carsten Walter _{1,

2,

3} , Michael Schwarze _{1,

2,

3} , Xiaohui Deng _{1,

2,

3} , Holger Dau _{3,

4,

5} , Matthias Driess _{1,

2,

3}

Affiliation

The design and development of economical and highly efficient electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) under alkaline conditions are vital in lowering the overall energy losses in alkaline water electrolysis. Here we present a nickel phosphite, Ni₁₁(HPO₃)₈(OH)₆, belonging to the unique class of phosphorus-based inorganic materials with striking structural features that have been explored for the first time in the reaction of electrocatalytic overall water splitting with a profound understanding of the system using in situ and ex situ techniques. When electrophoretically deposited, the nickel phosphite exhibited remarkable electrocatalytic activity, yielding considerably low overpotentials for both the OER and HER with extreme structural stability and enhanced durability in alkaline media. Apart from the attractive structural merits, the higher activity of nickel phosphite is mainly attributed to the formation of oxidized nickel species in the catalytic OER process, while subtle experimental evidence of the participation of phosphite anions for the acceleration of the HER with the support of Ni²⁺ cations as catalytically active sites is identified, which is highly compelling and has never been previously discovered. Finally, the bifunctionality of nickel phosphite was demonstrated by constructing an alkaline water electrolyzer with a low cell voltage and over 4 days of undiminishing stability. This work offers an appealing cost-effective system based on earth-abundant metals for water electrolysis and can be extended to other transition metal based homo- or hetero-bimetallic phosphites.

中文翻译：

具有结构通用性的亚磷酸镍，可作为坚固的双功能电催化剂，用于整体水分解†

在碱性条件下，用于氢气释放反应（HER）和氧气释放反应（OER）的经济高效的电催化剂的设计和开发对于降低碱性电解水的总能量损失至关重要。在这里，我们介绍一种亚磷酸镍Ni ₁₁（HPO ₃）₈（OH）₆，属于具有独特结构特征的磷基无机材料的独特类别，这是在电催化总水分解反应中首次探索的结构特征对原位和异位使用的系统有深刻的了解技术。电泳沉积时，亚磷酸镍显示出显着的电催化活性，对OER和HER产生极低的过电势，具有极高的结构稳定性和在碱性介质中的增强的耐久性。除了引人注目的结构优点外，亚磷酸镍的较高活性主要归因于催化OER过程中氧化镍物种的形成，而亚硝酸根阴离子参与了镍支持下促进HER加速的微妙实验证据。²⁺阳离子作为催化活性位点被确定，这是非常引人注目的，并且以前从未发现过。最后，通过构建一个低电池电压和超过4天的稳定性不变的碱性水电解槽，证明了亚磷酸镍的双功能性。这项工作提供了一种有吸引力的具有成本效益的系统，该系统基于用于水电解的地球上富足的金属，并且可以扩展到其他基于过渡金属的均一或杂双金属亚磷酸盐。

更新日期：2018-03-08

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