Abstract:
Green energy technology is becoming a future demand because of lowing the fossil fuel usage and its green gas pollution. Since the challenge is to convert and storage solar energy into the chemical energy, i.e. hydrogen or oxygen evolution reaction (HER or OER), how to characterize the correct intermediate steps of catalyst during electrochemial performance has been discussed intensively. Non-noble metals, such as transition metal oxide, have been mentioned because of two reasons: (a) cost and (b) abundance, although the efficiency and selectivity are not optimal and ideal during catalysis. Researches involving abundant hydroxyl groups on the surface, low-dimensional catalysis, and synthesis reaction apparently are the hot topics. In this talk, we would like to introduce graphene sheet to load the metal catalyst, not only by the stable lattice structure, but also by the unique electric conductivity. The key for bounding metal and graphene (or graphene oxide) is relied on the facial functional groups of hydroxyl, carboxyl, and epoxide, leading to the hydrophilic surface for further electrochemical reaction.[1] The correlation between the electronic structure and chemical bonding modification of graphene and graphene oxide has been studied by the microscopic and theoretical means, such as Kelvin Probe Force Microscope (KPFM), Scanning Transmission X-ray Microscopy (STXM), and Density functional theory (DFT).[2] The interaction between grown Co3O4 and graphene is characteristic of Co anchoring on the graphene, while carbon atom of graphene replaces oxygen ligands of Co3O4 as Co(CO)x formation at the solid-liquid interface. The requirement to do in-situ experiment in synchrotron beamline is important on the same environment and real-time observation. The electrochemical cell in soft and hard x-ray region will be demonstrated for diverse purposes and operation. Our work will provide the reduced graphene oxide membrane as the electrochemical window materials used the liquid cell, in order to demonstrate the modification of interface property of Co and its HER performance.
Keywords – In-situ electrochemical cell, Scanning transmission X-ray microscopy, Hydrogen evolution reaction, graphene oxide, Cobalt catalyst
References:
[1] J. J. Velasco Vélez, Yi-Ying Chin, Meng-Hsua Tsai, Oliver James Burton, Ruizhi Wang, Stephan Hofmann, Wei-Hao Hsu, Takuji Ohigashi, Way-Faung Pong, and Cheng-Hao Chuang “Evidence of synergistic electrocatalysis at a cobalt oxide /graphene interface through nano chemical mapping of scanning transmission X-ray microscopy” Chinese Journal of Physics 76, 135(2022)
[2] Jan Sebastian Dominic Rodriguez, Takuji Ohigashi, Chi-Cheng Lee, Meng-Hsuan Tsai, Chueh-Cheng Yang, Chia-Hsin Wang, Chi Chen, Way-Faung Pong, Hsiang-Chih Chiu, and Cheng-Hao Chuang* “Modulating chemical composition and work function of suspended reduced graphene oxide membranes through electrochemical reduction”. Carbon, 185, 410(2021).