Department of Chemical Engineering, University of Delaware, Newark, Delaware 19716, USA.
J Am Chem Soc. 2012 Feb 15;134(6):3025-33. doi: 10.1021/ja208656v. Epub 2012 Feb 1.
This work explores the opportunity to substantially reduce the cost of hydrogen evolution reaction (HER) catalysts by supporting monolayer (ML) amounts of precious metals on transition metal carbide substrates. The metal component includes platinum (Pt), palladium (Pd), and gold (Au); the low-cost carbide substrate includes tungsten carbides (WC and W(2)C) and molybdenum carbide (Mo(2)C). As a platform for these studies, single-phase carbide thin films with well-characterized surfaces have been synthesized, allowing for a direct comparison of the intrinsic HER activity of bare and Pt-modified carbide surfaces. It is found that WC and W(2)C are both excellent cathode support materials for ML Pt, exhibiting HER activities that are comparable to bulk Pt while displaying stable HER activity during chronopotentiometric HER measurements. The findings of excellent stability and HER activity of the ML Pt-WC and Pt-W(2)C surfaces may be explained by the similar bulk electronic properties of tungsten carbides to Pt, as is supported by density functional theory calculations. These results are further extended to other metal overlayers (Pd and Au) and supports (Mo(2)C), which demonstrate that the metal ML-supported transition metal carbide surfaces exhibit HER activity that is consistent with the well-known volcano relationship between activity and hydrogen binding energy. This work highlights the potential of using carbide materials to reduce the costs of hydrogen production from water electrolysis by serving as stable, low-cost supports for ML amounts of precious metals.
这项工作探索了通过在过渡金属碳化物基底上负载单层（ML）贵金属来大幅降低析氢反应（HER）催化剂成本的机会。金属组件包括铂（Pt）、钯（Pd）和金（Au）；低成本碳化物基底包括碳化钨（WC 和 W2C）和碳化钼（Mo2C）。作为这些研究的平台，已经合成了具有明确定义表面的单相碳化物薄膜，从而可以直接比较裸碳化物表面和 Pt 修饰碳化物表面的本征 HER 活性。研究发现，WC 和 W2C 都是 ML Pt 的极佳阴极支撑材料，其 HER 活性可与体相 Pt 相媲美，同时在恒电流 HER 测量中显示出稳定的 HER 活性。ML Pt-WC 和 Pt-W2C 表面具有优异的稳定性和 HER 活性，这一发现可以通过密度泛函理论计算得到解释，即碳化钨与 Pt 具有相似的体相电子特性。这些结果进一步扩展到其他金属覆盖层（Pd 和 Au）和支撑物（Mo2C），表明金属 ML 负载的过渡金属碳化物表面具有与众所周知的活性与氢结合能之间的火山关系一致的 HER 活性。这项工作强调了使用碳化物材料作为稳定、低成本的 ML 贵金属支撑物来降低水电解制氢成本的潜力。
