DRILL Interface Makes Ion Soft Landing Broadly Accessible for Energy Science and Applications

Abstract

Polyoxometalates (POM) have been deposited onto carbon nanotube (CNT) electrodes using benchtop ion soft landing (SL) enabled by a vortex-confined electrohydrodynamic desolvation process. The device is based on the dry ion localization and locomotion (DRILL) mass spectrometry interface of Fedorov and co-workers. By adding electrospray emitters, heating the desolvation gas, and operating at high gas flow rates, it is possible to obtain stable ion currents up to −15 nA that are ideal for deposition. Coupled with ambient ion optics, this interface enables desolvated ions to be delivered to surfaces while excluding solvent and counterions. Electron microscopy of surfaces prepared using the device reveal discrete POM and no aggregation that degrades electrode performance. Characterization of POM-coated CNT electrodes in a supercapacitor showed an energy storage capacity similar to that achieved with SL in vacuum. For solutions that produce primarily a single ion by electrospray ionization, benchtop SL offers a simpler and less costly approach for surface modification with applications in catalysis, energy storage, and beyond.

Insights from Adsorption and Electron Modification Studies of Polyoxometalates on Surfaces for Molecular Memory Applications

“…41 The time-and cost-intensive use of vacuum conditions, which are necessary to enable mass selection of ions, may be avoided for some applications requiring high coverage deposition of POMs by the use of an alternative dry ion localization and locomotion (DRILL) electrospray interface. 42 Multiple electrospray emitters, working at high flow rates of heated gases, are coupled with ambient ion optics for the removal of counterions and solvent molecules prior to deposition. For the deposition of POMs, the electrochemical performance of the prepared carbon nanotube (CNT) surfaces was found to be comparable to those generated by mass selected ion deposition in vacuum.…”

Multiplexing of Electrospray Ionization Sources Using Orthogonal Injection into an Electrodynamic Ion Funnel

“…Nonetheless, further improvement in the ion current from a single emitter is limited by the smallest droplet size that can be generated at a given flow rate and the maximum amount of charge carried by the ESI droplets, which is known as the Rayleigh limit. − Multiplexing of the ESI emitters is a promising strategy that has been employed to overcome this limitation. − One multiplexing strategy involves the development of ESI emitter arrays, which have been used both in analytical MS , and ESI-based propulsion. , In analytical MS, a circular 22-emitter array has been used to achieve more than a 2-fold improvement in the MS sensitivity . Ambient ion beam merging and focusing using specially shaped 3D-printed devices and counter-propagating beams provides an opportunity to manipulate and combine multiple ion beams before they enter the vacuum system. , Despite the significant progress in this field, multiplexing of ion beams still results in a substantial ion loss, which motivates the development of new multiplexing strategies.…”

Integrated photoelectrochemical energy storage cells prepared by benchtop ion soft landing

“…[22][23][24] A solid ionic liquid membrane separates the electrodes and ensures ionic transport To enable a meaningful comparison, POMs were deposited onto the ITO photocathode using both conventional solution-based drop casting and benchtop ion soft landing (SL), a versatile and highly-controlled approach for the modification of interfaces that efficiently removes neutral solvent molecules and counter ions. [25][26][27][28][29][30][31] SL of mass-and chargeselected POM anions in vacuum was shown to enhance the redox activity and stability of POMs at electrochemical interfaces due to more intimate contact between discrete individual POMs and the electrode and elimination of larger less active aggregates that form in the presence of counterions and solvent. The drop cast cathode, in comparison, contains both POM anions and strongly-coordinating counter cations (e.g., Na + ), which have been shown previously to reduce the redox activity of POMs.…”