Background
Transition metal hydroxyl oxides have great potential for a variety of catalytic oxidation reactions. FEOOH has received a lot of attention for its natural abundance and cost-effectiveness. At the same time, the integrated electrocatalyst can reduce the contact resistance, expose more active sites, and make the gas overflow more direct, but the one-step synthesis of the integrated FeOH electrode is still a big challenge. At the same time, there is still a problem that the morphological control mechanism of FeOH catalyst is not clear, which hinders its application and development.
Electrodeposition allows for fast and efficient preparation of supported catalysts with different compositions and structures by controlling the electrolyte composition and applying current and voltage. According to the Poisson-Boltzmann model, the electrical bilayer (EDL) repulsion between the negatively charged surfaces of a catalyst is mainly affected by its thickness (i.e., Debye length). Theoretically, changing the Debye length can change the EDL repulsion between two charged particles, which in turn affects the electrodeposition process.
Brief introduction of the results
The team of Professor Wang Lei and Professor Lai Jianping of Qingdao University of Science and TechnologyThe one-step electrodeposition method was used to synthesize the integrated FeOOH electrocatalyst introduced by CO, and the introduction of ions with different valence states was proposed to adjust the morphology of FEOOH by precisely adjusting the composition and thickness of EDL.
The density functional theory calculations and the corresponding physical characterization jointly prove that CO has strong electron trapping and hydrogen absorption capacity in the FeOH structure, which promotes the formation and stability of FeOOH. Without the introduction of other ions, Co-Feooh exhibits a block-like structure. The introduction of LA3+ as a competitive ion in the electrolyte can reduce the thickness of EDL and attenuate the repulsion during deposition, resulting in a denser bulk structure. Conversely, the introduction of low-valent K+ ions can increase the thickness of EDL and enhance the repulsion during deposition, resulting in the formation of a sheet-like structure.
The electrochemical results showed that compared with Co-FeOH and Co-FeoOh-La3+, Co-FeoOH-K+ exhibited the best OER activity in the alkaline electrolyte, and it only needed an overpotential of 292 mV to achieve a current density of 1000 mA·cm-2. The excellent catalytic activity is due to the thinner structure of co-feooh-k+, which can expose more active sites and a larger electrochemically active area.
In conclusion, the modulation strategy reported in this work can be used to synthesize and modulate the morphology of other transition metal hydroxyl oxides, and can be extended to other catalytic reactions.
**Reading guide
Figure 1Schematic diagram of the synthesis of Co-FeoOh, Co-Feooh-La3+, and Co-Feooh-K+.
Figure 2SEM images of (A) CofeoOH, (B) CofeOOH-LA3+, and (C) CofeOOH-K+;TEM images of (d) CofeoOH, (E) CofeOOH-LA3+, and (F) CofeOOH-K+;(g) Haadf-STEM images of CofeoOH-K+ and its EDX profile.
Figure 3(a) XRD spectra;(b) Raman spectra;(c) XPS full spectrum;(d) O 1S xps spectra;(e) CO2P XPS spectra;and (f) Fe 2PXPS spectra;Schematic models of (g) co-feooh and (h) co-feooh-h. Blue, green, pink, and white balls represent Fe, Co, O, and H atoms, respectively. (i) Hydrogenation formation energy at the O site on FeOH and Co-FeoOh.
Figure 4Growth model of Co-FeoOH (a) CoFe electrolyte;(b) M3+-containing COFE electrolytes and (c) M+-containing COFE electrolytes.
Figure 5Different catalysts in 1Study on the performance of electrocatalytic OER in 0 M KOH solution. (a) OER polarization curve;(b) Overpotential at current densities of 100 mA cm mA-2 and 1000 mA cm-2;(c) Tafel slope;(d) Impedance comparison chart;(e) ECSA comparison chart;(f) TOF comparison chart;(g) OER polarization curves of Co-FeoOH-K+ before and after multiple cycles, and durability evaluation by chronocurrent testing. (h) Comparison of the OER activity of Co-FeoOH-K+ with the previously reported electrocatalyst.
About the Author
Lai Jianping, Professor, School of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Doctoral Supervisor, Taishan Scholar Young Expert, Shandong Province. He is mainly engaged in the research of ultra-small nano (2-5 nm) metal-based energy electrocatalytic materials, and has published more than 100 SCI papers, among which he is the corresponding author and the first author in Nat commun.(2),chem, joule, acs cent. sci.,energy environ. sci.(2), adv. mater., adv. energy mater.(5), adv. funct. mater.(3),nano lett.(2),appl. catal. b: environ.(14) He has published more than 80 SCI** articles in internationally renowned journals and more than 60 articles with an impact factor of more than 10. He has presided over scientific research projects including Shandong Taishan Scholars Talent Project Project, Shandong Province Outstanding Youth, National Youth Program and other projects. As the main finisher, he has won the first prize of the Outstanding Scientific Research Achievement Award of the Ministry of Education, the second prize of the Natural Science Award of the Chinese Society of Particulates, the third prize of the Science and Technology Progress Award of the China Petroleum and Chemical Industry Federation, and the Excellence Award of the President of the Chinese Academy of Sciences. He is a member of the Youth Editorial Board of EcoEnergy magazine.
Wang LeiHe received his Ph.D. in Inorganic Chemistry from Jilin University in 2006. He has been engaged in the controllable synthesis of inorganic micro and nano materials and their applications in green energy and other related fields for a long time commun., angew. chem. int. ed., adv. mater., adv. energy mater., adv. funct. mater., energy storage mater., acs nano, nano energy, acs cent. sci，appl. catal. b: environ., science china chem.More than 400 SCI** articles have been published in important academic journals at home and abroad, such as Science China and Science Bulletin, among which the corresponding author's impact factor is greater than 100 of more than 180 articles. As the first to win the Science and Technology Progress Award of China Petroleum and Chemical Industry Federation, the Science and Technology Figure Award of China Renewable Energy Society and other awards.
Article information
liu j, shi y, gu y, et al. regulate electric double layer for one-step synthesize and modulate the morphology of (oxy)hydroxides. nano research, 2023