Spark-plasma-sintered porous electrodes for efficient oxygen evolution in alkaline water electrolysis
Spark-plasma-sintered porous electrodes for efficient oxygen evolution in alkaline water electrolysis
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DOI：
10.1016/j.electacta.2019.05.102
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发表时间：
2019-09
影响因子：
6.6
通讯作者：
T. Rauscher;C. I. Bernäcker;Stefan Loos;M. Vogt;B. Kieback;L. Röntzsch
中科院分区：
文献类型：
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作者：
T. Rauscher;C. I. Bernäcker;Stefan Loos;M. Vogt;B. Kieback;L. Röntzsch
采用短时间烧结技术火花等离子烧结与空间固定器相结合的方法制备了碱水电解用多孔电极。去除空间支架后，在金属衬底上获得了多晶Ni和纳米晶Ni- fe合金的高多孔层。电催化层的孔隙率和厚度可以通过空间支架体积含量和烧结工艺条件（例如施加的压力和温度）来控制。电极的活性表面可以通过双层充电确定的高达1120的粗糙度因子显着增加。多孔层对析氧反应（OER）是有效的，而活性受化学成分的影响很大。多孔Ni-Fe电极表现出极低的过电位，在0.3 A cm−2in高浓度KOH（29.9 wt.-%）在333 K时为230 mV 。除了高表面积外，多孔Ni-Fe层的效率还具有高的固有活度，导致低电流密度时的低Tafel斜率约为23 mV dec−1，高电流密度时的低Tafel斜率约为50 mV dec−1，以及高转换频率（TOF）约为3.4 s−1 0.3 V。多孔镍电极具有较低的本征活度、较高的tafe斜率和较低的TOF。此外，在间歇电解（高达1 A cm−2）100 h的实际操作条件下，多孔Ni-Fe电极具有优异的稳定性和活性。
Porous electrodes for alkaline water electrolysis were prepared by spark plasma sintering, a short-time sintering technique, in combination with a space holder method. After removal of the space holders, highly porous layers of polycrystalline Ni and of a nanocrystalline Ni-Fe alloy were obtained on a metallic substrate. Both porosity and thickness of the electrocatalytic layers can be controlled by the space holder volume content and the sintering process conditions, for example, the applied pressure and temperature. The active surface of the electrode can be increased significantly by a roughness factor of up to 1,120 determined by double layer charging. The porous layers are efficient towards oxygen evolution reaction (OER), whereas activity is greatly influenced by the chemical composition. The porous Ni-Fe electrodes exhibit an extremely low OER-overpotential of 230 mV at 0.3 A cm−2in highly concentrated KOH (29.9 wt.-%) at 333 K. Beside the high surface area, the efficiency of the porous Ni-Fe layer is characterized by a high intrinsic activity resulting in a low Tafel slope of around 23 mV dec−1at low and 50 mV dec−1at high current densities as well as a high turnover frequency (TOF) of approximately 3.4 s−1at 0.3 V. The porous Ni electrodes have a lower intrinsic activity with higher Tafel slopes and lower TOF. Moreover, an excellent stability and activity under realistic operating conditions of intermittent electrolysis (up to 1 A cm−2) for 100 h was proven for the porous Ni-Fe electrode.