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中美科学家制得使水分解成氢和氧的强劲催化剂
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中美科学家制得使水分解成氢和氧的强劲催化剂
诸平
据《纳米能源》（Nano Energy）杂志网站2017年7月20日报道（后附原文下载地址）,中美科学家合作研制出利用太阳能可以使水分解成氢（H2）和氧（O2）的强劲催化剂。催化剂的制备采用金属有机化学气相淀积法（metal-organic chemical vapor deposition简称MOCVD），如下图所示。
参加此项研究的科学家有来自成都的电子科技大学和美国赖斯大学(Rice University)和休斯敦大学（University of Houston）的研究人员。由赖斯大学和休斯敦大学的研究人员合作研制的使水分解为氢和氧的催化剂,并不需要昂贵的铂等贵金属。通过催化反应使为了水分解成氢气和氧气，是产生清洁能源的途径之一，此过程可以由赖斯大学和休斯顿大学的科学家开发的单个催化剂来进行简化。赖斯大学生产的电解膜，在休斯顿大学进行了测试，它是一种由Ni、石墨烯以及含有Fe、Mn和P元素的一种化合物组成的三层结构体。泡沫Ni为电解膜提供更大的表面积，导电石墨烯保护Ni退化,金属磷化物进行反应。有关催化剂的研究结果详见下图：
图1是形态学特征图
Fig. 1. Morphology characterization. SEM image of FeMnP on (A) NF and (B) GNF. (C) HRTEM of FeMnP. The inserted image is the Fast Fourier transform (FFT) image of the selected area in the dotted area. (D) SAED pattern of FeMnP. (E) Crystalline structure of hexagonal FeMnP. Grey spheres are P atoms; purple and yellow polyhedral are statistically mixed Fe and Mn atoms.
图2是FeMnP的组成与化学态
图3是电催化活性特征
Fig. 3. Electrocatalytic activity characterization. (A) The OER polarization curves in 0.1 M KOH at scan rate of 5 mV s−1. (B) The OER Tafel plots. (C) The HER polarization curves in 0.5 M H2SO4 and 0.1 M KOH at scan rate of 5 mV s−1. (D) The corresponding HER Tafel plots.
图4是稳定性特征及水分解
Fig. 4. Stability characterization and overall water splitting. (A) OER polarization curves of the FeMnP/NF and FeMnP/GNF electrodes in 0.1 M KOH at scan rate of 100 mV s−1, showing the 1st cycle and the 1000th cycle. (B) HER polarization curves of the FeMnP/NF and FeMnP/GNF electrodes in 0.5 M H2SO4 at scan rate of 100 mV s−1, showing the 1st cycle and the 1000th cycle. (C) I-V curves of the two electrode water splitting using FeMnP as bifunctional catalyst in 0.1 M KOH at scan rate of 5 mV s−1. (D) Long-term stability at a constant cell voltage of 1.6 V for 75 h using two FeMnP/NF electrodes or two FeMnP/GNF electrodes.
Fig. 5. Coverage-dependent hydrogen binding on (100) and (001)-Mn facets of FeMnP. Panels (A) and (B) show hydrogen adsorbed on FeMnP (100) at 1 ML and 7/6 ML, respectively. Panels (C) and (D) depict hydrogen adsorbed on FeMnP (001)-Mn surface at 1 ML and 9/8 ML, respectively. Panel (E) shows the calculated differential free binding energy of hydrogen ΔGH as a function of coverage. ML: monolayer.
补充材料中的图示如下，其中包括了金属有机化学气相淀积法的相关设备图示以及相关研究的谱图等。
更多信息请注意浏览原文或相关报道：
Zhenhuan Zhao, Desmond E. Schipper, Andrew P. Leitner, Hari Thirumalai, Jing-Han Chen, Lixin Xie, Fan Qin, Md Kamrul Alam, Lars C. Grabow, Shuo Chen, Dezhi Wang, Zhifeng Ren, Zhiming Wang, Kenton H. Whitmire, Jiming Bao. Bifunctional metal phosphide FeMnP films from single source metal organic chemical vapor deposition for efficient overall water splitting. Nano Energy, 2017, 39: 444–453. DOI: 10.1016/j.nanoen.2017.07.027
FeMnP was grown on Ni foam or graphene-wrapped Ni foam by MOCVD.
•Films were grown using the single-source molecular precursor FeMn(CO)8(μ-PH(μ-PH2).
•The films are an efficient bifunctional electrocatalyst for water splitting.
•FeMnP/graphene/Ni foam achieved a current density of 10 mA cm−2 at 1.55 V for overall water splitting.
•DFT investigation supports the outstanding electrocatalytic activity of FeMnP.
Developing stable and efficient bifunctional catalysts for overall water splitting into hydrogen and oxygen is a critical step in the realization of several clean-energy technologies. Here we report a robust and highly active electrocatalyst that is constructed by deposition of the ternary metal phosphide FeMnP onto graphene-protected nickel foam by metal-organic chemical vapor deposition from a single source precursor. FeMnP exhibits high electrocatalytic activity toward both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Utilizing FeMnP/GNF as both the anode and the cathode for overall water splitting, a current density of 10 mA cm−2 is achieved at a cell voltage of as low as 1.55 V with excellent stability. Complementary density functional theory (DFT) calculations suggest that facets exposing both Fe and Mn sites are necessary to achieve high HER activity. The present work provides a facile strategy for fabricating highly efficient electrocatalysts from earth-abundant materials for overall water splitting.
Supplementary material
Scientists produce robust catalyst to split water into hydrogen, oxygen
Splitting water for the cost of a nickel
https://blog.sciencenet.cn/blog-212210-1068484.html
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