Here, we demonstrate a general method of mediating the deposition of metal nanostructures on carbon substrates via reductive adsorbates. The adsorbates, quinone molecules, can achieve a well-defined surface coverage on a range of carbon substrates through one step of soaking. Upon electrochemical reduction, the adsorbates can function as surface-confined reductants to reduce metal cations for uniform anchorage of metal nanoparticles on carbon, which is not easily achievable via other electrochemical deposition. We apply the method to deposition of Ag and Pt and show the close correspondence between the coverage of the adsorbate and the amount of deposition as well as the dependence of the deposit structures on the quinone molecular structures. We further demonstrate the stability and the catalytic activity of the deposited Pt for catalyzing the hydrogen evolution reaction.
Min Lu,Yao Zheng,Yang Hu,Bolong Huang,Deguang Ji,Mingzi Sun,Jianyi Li,Yong Peng,Rui Si,Pinxian Xi,Chun-Hua Yan
The regulation of mechanism on the electrocatalysis process with multiple reaction pathways is more efficient and essential than conventional material engineering for the enhancement of catalyst performance. Here, by using oxygen evolution reaction (OER) as a model, which has an adsorbate evolution mechanism (AEM) and a lattice oxygen oxidation mechanism (LOM), we demonstrate a general strategy for steering the two mechanisms on various LaxSr1−xCoO3−δ. By delicately controlling the oxygen defect contents, the dominant OER mechanism on LaxSr1−xCoO3−δ can be arbitrarily transformed between AEM-LOM-AEM accompanied by a volcano-type activity variation trend. Experimental and computational evidence explicitly reveal that the phenomenon is due to the fact that the increased oxygen defects alter the lattice oxygen activity with a volcano-type trend and preserve the Co0 state for preferably OER. Therefore, we achieve the co-optimization between the activity and stability of catalysts by altering the mechanism rather than a specific design of catalysts.
Yucheng Liu,Haoran Sun,Jing Hou,Jinyin Bai,Lizhang Wang
In this work, β-PbO 2 /Ti and RuO 2 -IrO 2 /Ti anodes and Ti cathodes were employed to conduct electrocatalytic phenol degradation experiments at various current densities. The difference in degradation rates between the two anodes indicated that the oxygen evolution reaction (OER) is related to the organic matter concentration. Consequently, a coupling mechanism “active-site competition mechanism (ACM) + adsorbate evolution mechanism (AEM)” for anodic oxygen evolution was described. Based on this mechanism and experimental results, it can be concluded that the ACM influences the initial degradation rate, and the AEM affects final organic matter concentrations. DFT calculations showed that RuO 2 -IrO 2 exhibits excellent AEM activity attributed to the lower OER overpotential (0.7 V) and stronger adsorption energies of *O oxygenated intermediate (-1.52 eV). At the same time, RuO 2 -IrO 2 possesses slight thermodynamic reaction energy of ACM, which are 103.3, 31.6 and 89.5 kJ/mol. Therefore, the slower degradation rates and lower removal efficiency on RuO 2 -IrO 2 /Ti are owing to the better ACM and AEM activity. Then, electrocatalytic experiments at various pH were conducted to verify the conclusion that AEM affects final organic matter concentrations. Finally, this work has implications for a better understanding of the OER mechanism and provides theoretical guidance for improving the removal efficiency of organic pollutants.
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