Nowadays, substantial works have been devoted to electrochemical energy storage and conversion due to the increasing global energy demand. The individual nanowire/sheet electrochemical devices can establish an intrinsic relationship between the electrochemical performance and electronic transport. Meanwhile, it is a fantastic platform to tune the electrochemical behavior (including electrochemical energy storage and electrocatalytic) with external fields, which is meaningful on understanding the reaction mechanism and further developing new optimize strategy. Here, we highlight the recent developments of individual nanowire-sheet electrochemical devices in energy storage and catalysis.¹

In the electrocatalytic field, we designed an in-situ testing platform with individual Ni-graphene nanosheet based oxygen evolution reaction devices.² It is demonstrated that the oxygen acts as a barrier to significantly reduce the concentration of OH⁻ ions at catalyst surface, slowing down the charge transfer process and OER kinetics. By removing oxygen in the electrolyte, a significant decrease in Tafel slope of over 20% and an early onset potential of 1.344 V vs. RHE have been achieved. Afterwards, the individual electrocatalytic devices were applied to understand how does the external electric field tune the hydrogen evolution reaction (HER) behavior. Increasing the back gate voltage from 0 to 5 V, the overpotential of individual MoS₂ nanosheet decreases from 240 to 38 mV.³ Such strategy is further extended to VSe₂ nanosheet.⁴ Our results indicate that HER performance improves along with the increasing of the negative back gate voltage. Besides, charge transfer resistance and high-frequency time constant drop dramatically, which demonstrates a much faster charge transfer process.

Reference

1. Mai L*, Yan M, Zhao Y. Track batteries degrading in real time. Nature 2017, 546(7659): 469.
2. Wang P, Yan M*, Meng J, Jiang G, Qu L, Pan X, Mai L*, et al. Oxygen evolution reaction dynamics monitored by an individual nanosheet-based electronic circuit. Nature Communications 2017, 8.
3. Wang J, Yan M*, Zhao K, Liao X, Wang P, Pan X, Mai L*, et al. Field Effect Enhanced Hydrogen Evolution Reaction of MoS2 Nanosheets. Advanced Materials 2017, 29(7).
4. Yan M, Pan X, Wang P, Chen F, He L, Jiang G, et al. Field-effect tuned adsorption-dynamics of VSe2 nanosheet for enhanced hydrogen evolution reaction. Nano Letters 17(7): 4109.