The Mechanical Effect of MnO2 Layers on Electrochemical Actuation Performance of Nanoporous Gold

Abstract

This study investigated the electrochemical actuation behavior of nanoporous material during the capacitive process. The length change of nanoporous gold (npg) was in situ investigated in a liquid environment using the dilatometry technique. The mechanical effect of MnO2 layers was introduced in this work to improve the actuation characteristics of the npg samples. Our work found that the actuation behavior of npg sample could be significantly modulated with a covering of MnO2 layers. The electrochemical actuation amplitude was efficiently improved and strongly dependent on the thickness of MnO2 layers covered. Aside from the amplitude, the phase relation between the length change and the electrode potential was inverted when covering the MnO2 layer on the npg samples. This means the expansion of the npg samples and the contraction of samples covered with the MnO2 layer when electrochemical potential sweeps positively. A simple finite element model was built up to understand the effect of the MnO2 layer. The agreement between the simulation result and the experimental data indicates that the sign-inverted actuation-potential response of nanoporous gold contributes to the mechanical effect of MnO2. It is believed that our work could offer a deep understanding on the effect of the MnO2 layer on the electrochemical actuation and then provide a useful strategy to modulate the actuation performance of nanoporous metal materials.

Sensitivity Detection of Uric Acid and Creatinine in Human Urine Based on Nanoporous Gold

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Hierarchically Structured Nanoporous Palladium with Ordered/Disordered Channels for Ultrahigh and Fast Strain

“…The NP-Pd shows a microsheet-array-like hierarchically nanoporous (MAHNP) structure composed of array-like microsized channels/sheets and disordered nanosized networks. More importantly, the MAHNP-Pd exhibits an ultrahigh strain amplitude of 4.68%, which exceeds those of all bulk electrochemical metallic actuators reported so far. ,− ,− As benchmarked with unimodal NP-Pd, such an enhanced actuation performance of MAHNP-Pd strongly depends on the unique hierarchical structure, which provides the ordered channels to facilitate mass transport and large surface area for hydrogen adsorption/absorption and desorption.…”

“…However, their strain amplitudes are significantly smaller than those of polymers, and the strain rate is difficult to reach the level of artificial muscles (10 –3 –10 –1 s –1 ) . Extensive efforts have been dedicated to improve the actuation performance of metallic actuators: (i) fabricating fine nanoporous structure to increase specific surface area for charge storage or ion adsorption/desorption; , (ii) coating an oxide/polymer layer to obtain stable and large strains; ,− (iii) designing a hierarchically porous structure to achieve fast strain rate; , and (iv) using materials with excellent hydrogen adsorption/absorption capabilities. , Nevertheless, the strain amplitude of bulk electrochemical metallic actuators has not exceeded 4% . Thus, an enhanced actuation performance with large strain amplitude and fast response is highly desirable.…”

Electrocatalyst design for the conversion of energy molecules: electronic state modulation and mass transport regulation

“…The alloying of Pt, Pb and other transition metal elements not only reduces the amounts of noble metals, but also generates the alloying effect, ligand effect, etc. [61][62][63][64][65][66][67][68][69][70] The aforementioned effects can effectively change the position of the center of the low d-band of the metal active site relative to the E f , which can enhance the adsorption-desorption behavior of the active sites for intermediates. More importantly, in the process of forming the alloy, the lattice parameters of transition metals or Pt, Pd, etc.…”