Scanning Nanoelectrochemistry and Nanoelectrical Liquid ......High Spatial Sensitivity 11/15/2017 Bruker Confidential 8 Hynek et. al. InTech, 2014, DOI: 10.5772/572033 Nellist et al

Scanning Nanoelectrochemistry and Nanoelectrical Liquid Imaging with Nanoelectrode Probe

Teddy Huang, PhD Sr. Applications Scientist, Bruker Nano Surfaces, [email protected]

Outline

• Overview

• Nanoelectrode Probe

• AFM-SECM

• PeakForce SECM

• Force Volume SECM

• Contact Mode SECM

• Tapping Mode SECM

• Nanoelectrical Measurements in Liquid

• Conductive AFM

• PFM: Nano-Electromechanics

• Kelvin Probe Force Microscopy

• Conclusion

11/15/2017 2 Bruker Confidential

Pt

SiO2

r ~ 25 nm

h ~ 250 nm

Success from Collaboration


Applications Collaborators

PeakForce SECM

PF-TUNA in Liquid

Solar Fuels

Surface Chemistry

JCAP/Caltech

Universität Bayreuth (Germany)

CCI Solar

University of Oregon

University of Leeds (UK)

Battery

Brown University

General Motors R&D

Fujian Normal University (China)

Force Volume SECM Stanford University

Industrial Companies in China

PFM in Liquid East China Normal University

• Nanoelectrode Probe

• Scanning Nano-Electrochemistry

• Nanoelectrical Measurements in Liquid

Pt

SiO2

r ~ 25 nm

h ~ 250 nm

Some Publications

• Nellist et al. Nature Energy 2017, accepted

• Jiang et al. ChemSusChem 2017, DOI: 10.1002/cssc.201700893

• Nellist et al. Nanotechnology 2017, 28, 095711

• Huang et al. Bruker Application Note 2017

• Huang et al. Microscopy Today 2016, 24, 18

11/15/2017 4

Bruker Confidential

Nanoelectrode Probe


Active Tip for SECM (local EC studies) & Electrical Characterization in Liquid

• Probe

• Batch (wafer) manufactured

• Exposed tip height: ~ 250 nm

• End tip radius: ~ 25nm

• k = 1.5 N/m, f = 65 kHz

• Package

• Fully isolated, encapsulated in two parts glass

• Easy to handle, robust ESD protection

• Chemical resistant (pH 1-13 & battery solution)


Pt

SiO2

r ~ 25 nm

h ~ 250 nm 1 mm

Nellist et al. Nanotechnology 2017, 28, 095711

High Electrochemical Performance

• Robust for handling and electrochemistry:

[Ru(NH3)6]2+/3+: 4 rinse-and-dry cycles, 5 min

amperometry, and 29 CVs


5 mM [Ru(NH3)6]3+

Potential (V vs

Ag/AgCl)

Cu

rre

nt

(pA

)

[Fe(CN)6]4-/3-

50 CVs

2 hr i-t curve

[Fe(CN)6]3+/4+: 50 CVs and 2 hr amperometry

sub-pA noise level


High Spatial Sensitivity


Hynek et. al. InTech, 2014, DOI: 10.5772/57203


Force Curve

Line: Experiment

Symbols: Simulation

• Approach Curves

• Current vs tip-sample distance

• Inactive/active area: negative/positive feedbacks

• Kinetic quantification: shape vs. surface activity

• Consistent with simulation

• No leakage current

• Changes mostly occur within 150 nm

• High spatial sensitivity

• Consistent with diffusion layer structure

0

5

10 mM

[Ru(NH3)6]3+ [Ru(NH3)6]

2+

e

< 100 nm diffusion layer

PeakForce Scanning Electrochemical Microscopy


Scanning Electrochemical Microscopy (SECM)


• A tiny electrode brings electrochemistry to micro- or nano-scale

• Local EC characterizes active site, diffusion, ionic transport, permeability, etc.

• Resolutions are primarily defined by the probe electrode dimension

E vs Ref

E + ΔV vs Ref

O + e R

Sample

R O + e

SECM Applications


Mauzeroll et. al., Chem. Rev. 2016, 116, 13234

PeakForce Tapping


Probe is sinusoidally modulated at 1~2 kHz:

• No cantilever tuning required.

• Low and stable force, < 50 pN.

• Automatic image optimization.

• Quantitative NanoMechanics (QNM).

• Simultaneous nanoelectric capture.

Time Z position Separation

Electrics

Time

PF-TUNA PF-QNM

FSP

ASP

Contact High imaging force

Tapping Rely on resonance

F0

Fpeak PeakForce Tapping Precise force control

PeakForce Tapping: Application Examples


Small 2014, 10, 3257

DNA

Embedded CNT on P3HT lamellar

Leclere et al. Nanoscale, 2012, 4, 2705

Live E. Coli cells

SAM on Au

Electrochemistry

Microscopy Today 2016, 24, 18

PeakForce SECM


• Simultaneously multimodal imaging:

Topography, mechanics, conductivity, electrochemistry, etc.


Lift

Height

PeakForce AFM

Electrochemistry

Interleaved Scan Scanning NanoEC

PeakForce SECM Hardware

Boot Probe

Probe holder

Strain-released module AFM scanner

Resistor selector

Probe connection

EC cell

Temperature control (RT to 65 oC)

Huang et al. Microscopy Today 2016, 24, 18

• Low noise electronics, limited only by potentiostat

• Robust ESD protection

• Compatible with glovebox operation

• Wide range of chemical compatibility

11/15/2017 Bruker Confidential 15

Operation inside a glovebox

PeakForce SECM


• Multimodal imaging at 15 nm lift height

Si3N4 Pt

25 nm depth Si3N4

Contact Current

4.5 nN 9 nN 4.5 nN

SECM Current

7~10 nA 0.3 nA 0.3 nA

495 pA 290 pA 290 pA

15 nm

25 nm

40 nm

60 nm

150 nm

400 nm

Si3N4 Pt Si3N4

• Lift height-dependent current.

• Changes mostly occur within 100 nm lift height.

• Confirm the compact structure of the diffusion layer.

Defects on HOPG Electrode



Electrochemistry

Modulus Adhesion

Conductivity

r ~ 25 nm

Topography 250 nm

0.4 nm step 800 nm

4 nN difference 800 nm

900 nm x 600 nm

55 pA difference 800 nm

2~5 pA higher

Topography

Adhesion

SECM

PeakForce SECM Pt/p+-Si for Catalysis

• Settings:

• 10 mM [Ru(NH3)6]3+, 0.1M KCl

• Tip potential: -0.4 V vs AgQRE

• Sample potential: -0.1 V vs AgQRE

• Peak force: 700 pN; Scan rate: 0.2 Hz; Lift height: 100 nm;

• PeakForce Tapping is required to measure these loosely attached particles

• Contact current measures interfacial conductivity

• SECM current measures electrochemical activity


Topography Contact Current

SECM Current

Jiang et al. ChemSusChem, 2017 DOI: 10.1002/cssc.201700893

Force Volume Scanning Electrochemical Microscopy


Kinetic Quantification of Surface Reaction


3 µm

3 µm

3 µm

Si3N4

Pt

Inhomogeneous conductivity

Inhomogeneous electrochemical activity

Approach curves of distinct characteristics

Force Volume Quantitative mechanical mapping modes

• Linear ramping to collect the complete force curve from every tap

• Multiple property maps calculated

• Multiple ramp data channels acquired

• Ramp and hold functionality


Separation

Force Volume: 1Hz FastForce Volume156Hz

Force Volume SECM

• Array of approach curves for improved EC quantification.

• EC activity in function of distance to sample surface, in every pixel (mapping).

• Correlated topography, nanomechanics and nanoelectrics


0.75 Hz ramp rate on Z

62.5 nm / pixel

Topography

Force Curves

Approach Curves

Force Volume SECM Insulating Flake on Au Substrate

• Sample Courtesy: Liming Zhang, J. Tyler Meffordd, Andrew Akbashev, and William Chueh, Stanford University


Oxide Au

Force Volume SECM Density Plot

• Density plot shows which EC activities are most commonly present

• Two distinct areas are differentiated by the two density plots

• Sample Courtesy: Liming Zhang, J. Tyler Meffordd, Andrew Akbashev, and William Chueh, Stanford University

24 Bruker Confidential

Tip

Cu

rre

nt

(nA

)

Oxide

Au

11/15/2017

Ramp and Hold with FV-SECM


Pt

Si3N4

Pt

Si3N4

Fo

rce (

nN

) T

ip C

urr

en

t (n

A)

Tip

Cu

rren

t (p

A)

On Pt, positive feedback and electrically connected with the Pt electrode

On nitride, negative feedback and electrically disconnected with the Pt electrode

Nellist, M. R.; Laskowski, F. A. L.; Qiu, J.; Sivula, K.; Hamann, T.W.; Boettcher, S.W. Potential-sensing electrochemical atomic force microscopy

enables in-operando analysis of electrocatalysis during (photo)electrochemical water splitting. Accepted, Nat. Energy.

Nanoelectrode AFM probes enable the in-operando

measurement of surface electrochemical potentials

during oxygen evolution catalysis

1 µm 1 µm

CoPi on planar

Fe2O3

planar Fe2O3 CoPi

photoelectro-

deposition

• Catalytst voltage (Vtip) identical

whether on ITO or illuminated hematite

• Holes transfer from hematite to CoPi,

where water oxidation occurs Spatially resolved photovoltage!


Nanoelectrical Measurements in Liquid

AFM Nanoelectrical Measurements

11/15/2017 28 Bruker

• Bruker provides a versatile array of electrical techniques for a multitude of applications.

Conductivity/Resistivity C-AFM, TUNA, PeakForce-TUNA, SSRM

Electric Field EFM

Charge EFM, SCM

Surface Potential / Work Function KPFM, PeakForce KPFM

Carrier Density SCM, SSRM, sMIM, PeakForce-sMIM

Piezoelectricity PFM

PeakForce Nanoelectrical Measurements

11/15/2017 29 Bruker

• For previously AFM-inaccessible, delicate samples and adds correlated nanomechanical data

• Improve tip lifetime with hard samples

• Decrease sample wear with soft samples

• Improve resolution due to sharper tips & less sample damage

Electrics

Time

PeakForce TUNA (A) topography, (B) current, and (C) adhesion maps

reveal the influence of an embedded nanotube on P3HT lamellar ordering

and current pathways. Image size 500 nm.

Leclere et al. Nanoscale, 2012, 4, 2705

Nanoelectrical Liquid Imaging


Battery • Applications

• Energy research

• Bio-electricity

• Catalysis

• Sensing

• Challenges

• Compatibility:

Environment & chemicals

• Localized signals

• High S/N

Energy/Catalysis

Lee et al. Adv. Mater. 2014, 26, 4880

Bio-electricity

Kumar et al. ACS Appl. Mater. Interfaces, 2017, 9, 28406


• Probe and sample are fully immersed in solution

• High quality, localized signal

• Fully-insulated but the tip apex

• Conductive path to minimize stray capacitance

• High bandwidth, next-to-tip amplifier

100 µm

Nanoelectrical Liquid Imaging

11/15/2017 31 Bruker


TUNA & PeakForce TUNA in Liquid

PeakForce TUNA in Liquid (DMC) in Glove Box

• Sample was in DMC, a solvent for battery research

• Measurement was done inside a glove box

• Clearly differentiates exposed Pt on the current map

• I-V spectra confirms the difference in conductivity

• Negligible background current at nitride surface


1

2

3

Si3N4

Si3N4 Pt

1 2

3

Single line data, no averaging


PeakForce TUNA in Liquid in 1M KCl Aqueous Solution at High Bias

• Low parasitic currents on Si3N4:

• At -0.5V: 1.06 pA

• At +0.5V: 0.07 pA

• Low current noise level: ~1 pA


0.5V

-0.5V

0.5V

-0.5V

Si3N4 Pt

Si3N4 Pt

Si3N4 Pt

PeakForce TUNA in Liquid Interfacial Energetics on a Photoelectrode

• Semiconductor/Metal Junction in Liquid

• Sample shows diode behavior in air

• I-V characteristics in H2O totally changes


Air

Liquid

Liquid on SiO2

-250 pA

100 pA

120 nm

120 nm

Sample bias: 0.3 V


Pt/p+-Si: PeakForce SECM


Topography

Contact Current

SECM Current

• Resistive interface: contact current (interfacial conductivity) is correlated with SECM current

• Conductive interface: EC activity is compared (e.g. #2 vs. #3, higher contact current but lower SECM current)

Contact Current (nA)

1.4 1.6 1.8 4.0 5.0

SE

CM

Curr

ent (n

A)

1.40

1.45

1.50

1.55

1.60

Col 1 vs Col 2 Col 1 vs Col 2: 1.5500

Col 1 vs Col 2: 5.1900

#2

#3


Pt

SiO2

Si

e

O R

e


PeakForce KPFM in Liquid

PeakForce KPFM in Liquid (H2O, 1 mM KCl, or DMC)


Pt Pt

Si3N4 Si3N4

Pt Pt

Si3N4 Si3N4

• In Air: ~125 mV difference

• In H2O: ~150 mV difference

Pt Si3N4 Si3N4

Si3N4 Pt

Pt


Piezoresponse Force Microscopy (PFM) in Liquid

Web: http://spec-lab.ecnu.edu.cn/ E-mail: [email protected]

Air- at contact resonance H2O-Off resonance H2O - at resonance

0.5 M NaCl 0.01 mM NaCl 0.1 mM NaCl 1 M NaCl

High-Resolution Electromechanical Imaging of Bio-compatible

Ferroelectric Materials in Air, Water and NaCl Electrolyte.

• Slides contributed from Anyang Cui, East China Normal University.

• Measurements were in collaboration with Bruker.

• Cui & Hu et al., manuscript in preparation.

Nanoelectrode from Bruker

Unpublished Results, Manuscript in Preparation

Anyang Cui

Phase Contrast at Contact Resonance


Air H2O

1 mM 10 mM

H2O

Air

1 mM

Measurements were in collaboration with Cui&Hu et. al. at ECNU in China

Air H2O 1 mM 10 mM

2 µm 2 µm 2 µm 2 µm

• Sample: PPLN; Electrolyte: NaCl; Image Force: 100 nN

Conclusion

• Bruker’s new AFM-SECM probe technology improves

SECM lateral resolution by orders of magnitude and

opens the door to new measurements on individual

nanoparticles, -phases, and –pores

• PeakForce SECM enables the highest spatial resolution

and multi-modal imaging on soft and fragile samples

• Force Volume SECM allows for improved kinetic

quantification and provides 3D electrochemical

mapping, through capturing a complete data cube

• PeakForce nanoelectrical measurements in liquid

provide new capabilities for visualization of electrical

processes in solution



Pt

SiO2

r ~ 25 nm

h ~ 250 nm

© Copyright Bruker Corporation. All rights reserved.

www.bruker.com

43 Bruker Confidential

KPFM Sensitivity Scales with Q/k

• In liquid, the sensitivity is about 20x lower (vs. air) with these cantilevers


f0 ~ 62 kHz Q ~ 215

f0 ~ 29 kHz Q = 10

• In di-H2O • In Air

Tapping Mode (Z Modulation)


• Cells were over grown and covered the whole petri dish

• SECM probe successfully imaged the topography of live cells without sample damages

Defects on HOPG Electrode


800 nm 800 nm

Topography Electrochemistry

Documents

Scanning Nanoelectrochemistry and Nanoelectrical Liquid ......High Spatial Sensitivity 11/15/2017 Bruker Confidential 8 Hynek et. al. InTech, 2014, DOI: 10.5772/572033 Nellist et al