Abstract
The ability to vary the temperature of an electrochemical cell provides opportunities to control reaction rates and pathways and to drive processes that are inaccessible at ambient temperature. Here, we explore the effect of temperature on electrochemical etching of Ni–Pt bimetallic nanoparticles. To observe the process at nanoscale resolution we use liquid cell transmission electron microscopy with a modified liquid cell that enables simultaneous heating and biasing. By controlling the cell temperature, we demonstrate that the reaction rate and dissolution potential of the electrochemical Ni etching process can be changed. The in situ measurements suggest that the destabilization of the native nickel oxide layer is the slow step prior to subsequent fast Ni removal in the electrochemical Ni dissolution process. These experiments highlight the importance of in situ structural characterization under electrochemical and thermal conditions as a strategy to provide deeper insights into nanomaterial transformations as a function of temperature and potential.
Highlights
Temperature is known to provide a powerful control knob in tuning the reaction pathways and nal products of electrochemical reactions
This simple design is capable of simultaneous heating and electrochemical biasing using a two-electrode system comprised of a working electrode and combined reference/counter electrode
Initial characterization by scanning transmission electron microscopy (TEM) (STEM) and energydispersive X-ray spectroscopy (EDX) chemical mapping show structure and composition consistent with what is expected from synthesis with atomic percentages of 90% Ni and 10% Pt (Fig. 1E and Electronic supplementary information (ESI) Section 1†)
Summary
Temperature is known to provide a powerful control knob in tuning the reaction pathways and nal products of electrochemical reactions. Small differences in temperature can cause dramatic changes in reaction mechanisms[1,2] and make new reaction pathways accessible, such as intercalation processes at elevated temperature.[3] Temperature has a important role in battery reactions: for example, lithium ion batteries show slow kinetics at low temperatures and materials degradation at higher temperatures, both of these affecting performance, safety, and cycle life.[4] Multiple effects can play a role simultaneously: for corrosion processes, elevated temperatures increase the tendency for material oxidation and sul dation while speeding up the diffusion rate and mass transport rate between the material's surface and its environment.[5] As a result, the outcome of many electrochemical reactions is temperature-dependent. Measurements over a range of temperature can provide thermodynamic and kinetic parameters such as standard reduction potentials, activity coefficients and equilibrium constants,[7] an approach that has proved useful in technological applications
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