Cobalt (II) oxide for efficient glycerol electrooxidation for formic acid coupled with hydrogen production

全文速览：在电解水系统中，阳极析氧反应（OER）的动力学速度很慢，通常需要高过电位，导致大量能源消耗。在阳极用甘油氧化反应（GOR）取代OER被认为是解决这一问题的潜在策略。本文设计了泡沫镍（CoO/NF）CoO的原位生长，以实现GOR的高性能。结果表明，在1.3 V电压下，甲酸（FA）的选择性达到93.3%，GOR Faradaic效率达到91.3%。在阳极上组装了 CoO/NF 电极，在阴极组装了商业 Pt/C。该流通池仅需要1.6 V的电池电压即可实现≈100 mA cm−2的电流密度，并且在工作108小时后表现出优异的稳定性，电流衰减为0.56%。更重要的是，在这个当前的密度水平下，实现了显著的FA和H2生产率，通过一系列表征深入研究了CoO对甘油的催化途径和机理。通过与电解水偶联制氢，有助于同时获得氢气和高附加值产品。

研究亮点：

1.CoO用于甘油电氧化，对甲酸具有高选择性

2.揭示了COO/NF电极上GOR过程的机理

3.利用流动池，在1.6 V时实现了100 mA cm-2的电流密度

Fig. 1. (a) Schematic of the synthesis process of CoO/NF and its application. (b) XRD patterns of CoO/NF and CCOH/NF compared with standard cards. (c, d) SEM images of CoO/NF. (e, f) TEM and HRTEM images of CoO.

Fig. 2. (a) LSV curves of CoO/NF electrode in GOR and OER. (b) Tafel slopes of CoO/NF electrode in GOR and OER. (c) Voltage difference between GOR and OER at different current densities. (d) CoO/NF electrode and Performance comparison of other GOR catalysts. (e) HPLC spectra of electrolytic glycerol at 1.3 V using a CoO/NF electrode. (f) FE of GOR and FA selectivity under different voltages. (g) Possible electrooxidative degradation pathway of GLY by CoO/NF electrode.

Fig. 3. In situ Raman spectra of CoO/NF electrodes at different voltages for (a, b) GOR and (c, d) OER.

Fig. 4. (a, b) XPS spectra of CoO/NF electrodes before and after GOR and OER tests. (c) XRD patterns of CoO/NF after GOR and OER. SEM images of CoO/NF after (d) GOR and (e) OER. (f) Schematic illustrations of spontaneous OER and GOR on CoO. The voltage of all GOR and OER was 1.55 V

Fig. 5. (a) Schematic diagram of homemade flow cell. (b) LSV curves of GOR and OER using flow cells. (c, d) The amount of FA and H2 generated versus the corresponding FEs. (e) Stability test of the CoO/NF in the flow cell at 1.6 V.