US EPA

5063568 

Journal Article 

Depth-Profiling Microanalysis of CoNCN Water-Oxidation Catalyst Using a λ = 46.9 nm Plasma Laser for Nano-Ionization Mass Spectrometry 

Müller, R; Kuznetsov, I; Arbelo, Y; Trottmann, M; Menoni, CS; Rocca, JJ; Patzke, GR; Bleiner, D 

2018 

Yes 

Analytical Chemistry
ISSN: 0003-2700
EISSN: 1520-6882 

90 

15 

9234-9240 

English 

29963853 

10.1021/acs.analchem.8b01740 

WOS:000441476600067 

Nanoscale depth profiling analysis of a CoNCN-coated electrode for water oxidation catalysis was carried out using table-top extreme ultraviolet (XUV) laser ablation time-of-flight mass spectrometry. The self-developed laser operates at λ = 46.9 nm and represents factor of 4 reduction in wavelength with respect to the 193 nm excimer laser. The reduction of the wavelength is an alternative approach to the reduction of the pulse duration, to enhance the ablation characteristics and obtain smaller quasi-nondestructive ablation pits. Such a XUV-laser ablation method allowed distinguishing different composite components of the catalyst-Nafion blend, used to modify a screen-printed carbon electrode surface. Chemical information was extracted by fragment assignment and relative amplitude analysis of the mass spectrometry peaks. Pure Nafion and the exposed carbon substrate were compared as references. Material specific fragments were clearly identified by the detected nonoverlapping mass-to-charge peaks of Nafion and CoNCN. Three dimensional mapping of relevant mass peak amplitudes was used to determine the lateral distribution and to generate depth profiles from consecutive laser pulses. Evaluating the profiles of pristine electrodes gave insight into fragmentation behavior of the catalyst in a functional ionomer matrix and comparison of post-catalytic electrodes revealed spots of thin localized Co residues.