Monitoring surface transformations of metal carbodiimide water oxidation catalysts by operando XAS and Raman spectroscopy.
Rafael J MüllerJinggang LanKarla LienauRené MoréC A TrianaMarcella IannuzziGreta R PatzkePublished in: Dalton transactions (Cambridge, England : 2003) (2018)
Transition metal carbodiimides MNCN (M = Co, Ni, Co0.9Ni0.1, Mn and Cu), were studied by simultaneous operando Raman and X-ray absorption spectroscopy (XAS) with focus on surface oxide detection during electrocatalytic water oxidation. As a proof of concept, easily modifiable screen-printed electrodes were used in this unified operando synchrotron setup for a trade-off between convenience of electrochemical anodization and spectroscopic data acquisition. Monitoring of chemical and structural transformations at the electrode surface during initial anodic electrode polarization shows stability for MNCN with M = Co, Ni, Co0.9Ni0.1 and Mn. While MnNCN is inactive, CoNCN emerges as the most active representative of the series. CuNCN displays pronounced side reactions and the formation of a surface copper oxide layer leading to lower current density attributed to water oxidation, as evident from an irreversible variation of the CuNCN redox behaviour in rotating ring-disc voltammetry. Furthermore, the accompanying structural and vibrational spectroscopy properties of the different MNCN compounds were explored with complementary ex situ analytical methods.
Keyphrases
- transition metal
- metal organic framework
- raman spectroscopy
- high resolution
- solid state
- hydrogen peroxide
- electron transfer
- label free
- single molecule
- computed tomography
- magnetic resonance imaging
- gold nanoparticles
- molecular docking
- carbon nanotubes
- reduced graphene oxide
- electronic health record
- molecular dynamics simulations
- molecularly imprinted
- room temperature
- big data
- visible light
- machine learning
- contrast enhanced
- aqueous solution
- molecular dynamics
- liquid chromatography