Carl Osby M. Mariano, Russell Hizon Clemente, Meng-Hsuan Tsai, Yi-Ying Chin, Jin-Ming Chen, Jyh-Fu Lee, Ying-Jui Lu, Chien-Ming Chen, Po-Tuan Chen, and Cheng-Hao Chuang PRX Energy 3, 033005 – Published 18 September 2024
Boosting Hydrogen Production: The Role of rGO in Co Catalysts
To enhance both the chemical stability and catalytic activity of cobalt (Co) in the hydrogen evolution reaction (HER), we’ve successfully incorporated reduced graphene oxide (rGO) into our cobalt catalyst. This approach effectively contributes to the goal of green and sustainable hydrogen production.
Our findings, derived from in situ mass spectrometry data, show that the Co/rGO system boosts hydrogen production by 3.8 times compared to a single Co catalyst. A combined analysis using in situ soft X-ray and hard X-ray spectroscopy reveals a progressive chemical evolution within the Co-3d and Co-4p electronic orbitals. The underlying contribution of rGO directly influences the distinct catalytic processes occurring on the Co surface.
This unique detection highlights a phase transformation from initial low and intermediate oxidation states to higher oxidation states, followed by the actual hydrogen evolution and deoxygenation processes. Critically, the presence of intermediate Co⁰ is directly linked to the efficiency of hydrogen generation.
Furthermore, theoretical calculations confirmed the energetic implications behind the adsorption of Co–O(H) and Co–H species, as well as the desorption of H₂ molecules. In high-energy X-ray spectroscopy analysis, a two-dimensional analysis map of distance (R) and wave vector (k) identified two regions: metallic Co and Co–O(H).
Density Functional Theory (DFT) calculations suggest that introducing rGO lowers the catalytic energy barrier, leading to improved regenerability and stability of the Co–H adsorption catalyst. This, in turn, enhances the Volmer-Heyrovsky performance during the HER.
Our experimental data, including in situ mass spectrometry, soft X-ray, and hard X-ray experiments, provide compelling evidence for the improved HER performance. This research offers a deep dive into the correlation between Co and OH/H bonds, meticulously analyzing their chemical composition, electronic structure, and related active processes. By conducting a series of cutting-edge in situ experiments and DFT calculations, we’ve gained crucial insights into the behavior of composite materials in electrocatalytic reactions.