Suchergebnisse

Enzymes can perform complex multistep cascade reactions by linking multiple distinct catalytic sites via substrate channeling. We mimic this feature in a generalized approach with an electrocatalytic nanoparticle for the carbon dioxide reduction reaction comprising a Ag core surrounded by a porous Cu shell, providing different active sites in nanoconfined volumes. The architecture of the nanozyme provides the basis for a cascade reaction, which promotes C−C coupling reactions. The first step occurs on the Ag core, and the subsequent steps on the porous copper shell, where a sufficiently high CO concentration due to the nanoconfinement facilitates C−C bond formation. The architecture yields the formation of n-propanol and propionaldehyde at potentials as low as −0.6 V vs RHE. ; W.S. is grateful for financial support by the Deutsche Forschungsgemeinschaft (EXC-2033-390677874) and the European Research Council (ERC) under the European Union's Horizon 2020 Research and Innovation Programme (grant agreement no. 833408). This work was supported by the DAAD in the framework of the PPP project 57446293 as well as the Ruhr University Research school PLUS through a research stay of P.W. at UNSW, funded by Germany's Excellence Initiative (DFG GSC 98/3). This research was financially supported by the Australian Research Council of Centre of Excellence in Convergent Bio-Nano Science and Technology (CE140100036), the ARC Australian Laureate Fellowship (FL150100060), the Discovery Project (DP190102659), and the Mark Wainwright Analytical Centre (MWAC) at UNSW. This work used the facilities supported by Microscopy Australia at the Electron Microscope Unit at UNSW. The authors are grateful to Dr. Douglas Lawes for discussion and assistance with 1H NMR experiments. P.B.O'M. acknowledges the Australian Government Research Training Program Scholarship for financial support. P.W. is grateful to the Association of the Chemical Industry e.V. (VCI) for funding of the Ph.D. fellowship.

Bimetallic silver-copper electrocatalysts are promising materials for electrochemical CO2 reduction reaction (CO2RR) to fuels and multi-carbon molecules. Here, we combine Ag core/porous Cu shell particles, which entrap reaction intermediates and thus facilitate the formation of C2+ products at low overpotentials, with gas diffusion electrodes (GDE). Mass transport plays a crucial role in the product selectivity in CO2RR. Conventional Hcell configurations suffer from limited CO2 diffusion to the reaction zone, thus decreasing the rate of the CO2RR. In contrast, in the case of GDE-based cells, the CO2RR takes place under enhanced mass transport conditions. Hence, investigation of the Ag core/porous Cu shell particles at the same potentials under different mass transport regimes reveals: (i) a variation of product distribution including C3 products, and (ii) a significant change in the local OH- activity under operation. ; This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement CasCat [833408]) as well as from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) in the framework of the research unit FOR 2397e2 (276655237). C.A. acknowledges funding by the BMBF in the framework of the NanomatFutur project "MatGasDif" (03XP0263). The Australian team acknowledges funding from the Australian Research Council (DP190102659, RDT, WS and DP210102698, JJG). Open Access funding enabled and organized by Projekt DEAL.

Scanning electrochemical cell microscopy (SECCM) is increasingly applied to determine the intrinsic catalytic activity of single electrocatalyst particle. This is especially feasible if the catalyst nanoparticles are large enough that they can be found and counted in post-SECCM scanning electron microscopy images. Evidently, this becomes impossible for very small nanoparticles and hence, a catalytic current measured in one landing zone of the SECCM droplet cannot be correlated to the exact number of catalyst particles. We show, that by introducing a ruler method employing a carbon nanoelectrode decorated with a countable number of the same catalyst particles from which the catalytic activity can be determined, the activity determined using SECCM from many spots can be converted in the intrinsic catalytic activity of a certain number of catalyst nanoparticles. ; This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement CasCat [833408]) as well as from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie MSCA-ITN Single-Entity Nanoelectrochemistry, Sentinel [812398]. S. S. and C. A. acknowledge the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) within the project [440951282]. X. X. C. acknowledges financial support from the Liaoning BaiQianWan Talents Program, China (No. 2019B042), and the Excellent Young Scientific and Technological Talents Project of Educational Department of Liaoning Province, China (No. 2020LNQN07). We acknowledge Prof. Patrick Unwin from the University of Warwick for providing the initial control software (WEC-SPM) for our SECCM experiments.

Cu-based catalysts have shown structural instability during the electrochemical CO2 reduction reaction (CO2RR). However, studies on monometallic Cu catalysts do not allow a nuanced differentiation between the contribution of the applied potential and the local concentration of CO as the reaction intermediate since both are inevitably linked. We first use bimetallic Ag-core/porous Cu-shell nanoparticles, which utilise nanoconfinement to generate high local CO concentrations at the Ag core at potentials at which the Cu shell is still inactive for the CO2RR. Using operando liquid cell TEM in combination with ex situ TEM, we can unequivocally confirm that the local CO concentration is the main source for the Cu instability. The local CO concentration is then modulated by replacing the Ag-core with a Pd-core which further confirms the role of high local CO concentrations. Product quantification during CO2RR reveals an inherent trade-off between stability, selectivity and activity in both systems. ; W. S. is grateful for financial support by the Deutsche Forschungsgemeinschaft under Germany's Excellence Strategy – EXC 2033 – 390677874 – RESOLV and the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (CasCat; grant agreement No. 833408). This work was supported by the DAAD in the framework of the PPP project 57446293 as well as the Ruhr University Research School PLUS through a research stay of P. W. at UNSW. This research was financially supported by the Australian Research Council of Centre of Excellence in Convergent Bio-Nano Science and Technology (CE140100036), the ARC Laureate Fellowship (FL150100060) and the Discovery Project (DP190102659). The Mark Wainwright Analytical Centre (MWAC) at UNSW. This work used the facilities supported by Microscopy Australia at the Electron Microscope Unit at UNSW. Wei Xia is acknowledged for his contribution to the CO measurements. P. B. O'M. acknowledges the Australian Government Research Training Program Scholarship for ...