Superwetting Nanoarray Electrodes for Gas-Involved Electrocatalysis

Superwetting Nanoarray Electrodes for Gas-Involved Electrocatalysis

Yingjie Li,  Wenwen Xu, Zhiyi Lu, Xiaoming Sun*

Beijing University of Chemical Technology, Beijing 100029, China, Email: sunxm@mail.buct.edu.cn

Electrochemical gas-involved reactions can be divided into two types: gas-evolution reaction and gas-consumption reaction, both of which are crucial for a variety of energy conversion processes and industries (e.g. HER and ORR). For gas-evolution reaciton, if generated gas bubbles pin at the electrode surface and cannot escape from the surface in time, the accumulated bubbles will reduce the effective electrode surface area, increase diffusion resistance and enlarge polarization effect, resulting in more energy consumption. How to construct a novel electrode to promote gas bubble release is critical for improving the electrochemical efficiency besides activity improvement. Inspired from bio-inspired superwetting surfaces, we found that the interface behavior of electrode could be tuned by surface architecture construction, for example, transferring from aerophobic to superaerophobic by engineering a series of nanoarray electrode, eg. MoS₂ (Fig. 1), pine-shaped Pt, NiFe LDHs and Cu films ^[1-7]. This kind of superaerophobic electrodes could decrease the critical size of gas overflowing from the surface by cutting the three phase contact lines into discontinue dots, and thus reduce the diffused impedance and maintain the integrity of the solid−liquid interface that is necessary for electrocatalysis (e.g. water splitting and hydrazine fuel cells). On the other hand, for gas-consumption reaction, the construction of nanoarray ¡°superaerophilic¡± electrode could accelerate gas diffusion to reaction zone via gas-phase to solve the issue of low solubility and slow diffusion of gases in traditional electrocatalysiss reaction system with limited current density (eg., ORR).  Therefore, the construction of superwetting nanoarray electrodes is imperative to improve gas transport at electrodes surface and to enhance activity and stability of electrodes.

Fig. 1 (A) Schematic illustration of adhesion behaviors of gas bubbles on flat film (left) and nanostructured film (right), (B) and (C) Adhesive forces measurements of the gas bubbles on flat and nanostructured MoS₂ films, (D) Polarization curves (without IR-correction) of MoS₂ and Pt/C catalysts (E) Stability testing of flat and nanostructured MoS₂ electrodes

References

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[2] Y. Li, H. Zhang, T. Xu, Z. Lu, X. Wu, P. Wan, X. Sun, L. Jiang. Adv. Funct. Mater. 25 (2015), 1737-1744.

[3] Z. Lu, M. Sun, T. Xu, Y. Li, W. Xu, Z. Chang, Y. Ding, X. Sun, L. Jiang. Adv. Mater. 27 (2015), 2361-2366.

[4] X. Liu, Z. Chang, L. Luo, T. Xu, X. Lei, J. Liu, X. Sun. Chem. Mater., 26 (2014), 1889-1895.

[5] M. Sun , Z. Lu , L. Luo, Z. Chang ,  X. Sun. Nanoscale, 8 (2016), 1479-1484

[6] W. Xu, Z. Lu, P. Wan, Y. Kuang,  X. Sun. Small, 12 (2016), 2492¨C2498

[7] M. Jiang, Y. Li, Z. Lu, X. Sun,  X. Duan. Inorg. Chem. Front. 2016, DOI: 10.1039/C5QI00232J.

Biography

Professor Xiaoming Sun gained his B.S. degree and Ph.D. in Department of Chemistry, Tsinghua University in 2000 and 2005, respectively. After postdoctoral work at Stanford University, he joined State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology at 2008. His main research interests focus on separation and assembly of inorganic nanostructures, synthesis and separation of carbon nanomaterials and their composites, and structure control, opto-/electro-property investigations of nanoarrays and  superwetting nanoarray electrodes for energy sciences. He has authored 63 journal articles (eg. J. Am. Chem. Soc., Angew. Chem. Int. Ed., Adv. Mater., ACS Nano.), which have been cited >4600 times.