Sheng Siyu, Shi Bairu, Wang Cheng, Luo Liang, Lin Xiao, Li Pengsong, Chen Fanhong, Shang Zhicheng, Meng Hong, Kuang Yun, Lin Wen-Feng, Sun Xiaoming
State Key Laboratory of Chemical Resource Engineering, Beijing Advanced Innovation Centre for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China.
ACS Appl Mater Interfaces. 2020 May 20;12(20):23627-23634. doi: 10.1021/acsami.0c04796. Epub 2020 May 8.
The bubbles electrochemically generated by gas evolution reactions are commonly driven off the electrode by buoyancy, a weak force used to overcome bubble adhesion barriers, leading to low gas-transporting efficiency. Herein, a Janus electrode with asymmetric wettability has been prepared by modifying two sides of a porous stainless-steel mesh electrode, with superhydrophobic polytetrafluoroethylene (PTFE) and Pt/C (or Ir/C) catalyst with well-balanced hydrophobicity, respectively, affording unidirectional transportation of as-formed gaseous hydrogen and oxygen from the catalyst side to the gas-collecting side during water splitting. "Bubble-free" electrolysis was realized while "floating" the Janus electrode on the electrolyte. Antibuoyancy through-mesh bubble transportation was observed while immersing the electrode with the PTFE side downward. The wettability gradient within the electrode endowed sticky states of bubbles on the catalyst side, resulting in efficient bubble-free gas transportation with 15-fold higher current density than submerged states.
由析气反应电化学产生的气泡通常通过浮力从电极上排出，浮力是一种用于克服气泡粘附障碍的微弱力，导致气体传输效率低下。在此，通过分别用超疏水聚四氟乙烯（PTFE）和具有良好平衡疏水性的Pt/C（或Ir/C）催化剂修饰多孔不锈钢网电极的两侧，制备了具有不对称润湿性的Janus电极，使得在水分解过程中形成的气态氢和氧从催化剂侧单向传输到气体收集侧。在将Janus电极“漂浮”在电解质上时实现了“无气泡”电解。当将PTFE侧朝下的电极浸入时，观察到了通过网孔的抗浮力气泡传输。电极内的润湿性梯度赋予了催化剂侧气泡的粘性状态，从而实现了高效的无气泡气体传输，电流密度比浸没状态高15倍。
