Germanomolybdate (GeMo12O404−) Modified Carbon Nanotube Composites for Electrochemical Capacitors

• GeMo12O404− (GeMo) was deposited onto MWCNT to fabricate capacitive electrodes.
• GeMo electrode showed excellent conductivity and 6X the capacitance of bare MWCNT.
• GeMo was superimposed with PMo12O403− or SiMo12O404− on dual-layer electrodes.
• Dual-layer electrodes showed combination of both molecules and 12X bare capacitance.

Keggin type germanomolybdate, GeMo12O404− (GeMo), was deposited onto multi-walled carbon nanotubes (MWCNT) via layer-by-layer (LbL) deposition to form composite electrodes for electrochemical capacitors (ECs). The GeMo composite electrode demonstrated charge storage six times greater than that of the bare MWCNT electrode while maintaining excellent conductivity and cycling stability. GeMo also demonstrated charge storage complementary to that of the commercial Keggin type POMs, PMo12O403− (PMo) and SiMo12O404− (SiMo). Dual-layer coatings superimposing GeMo with either PMo or SiMo showed an additive combination of both active layers, which resulted in cyclic voltammograms (CVs) with overlapping redox features and charge storage twelve times greater than that of the bare MWCNT electrode. Scanning Electron Microscopy (SEM) demonstrated successful single and dual layer coating of POMs on MWCNT with high coverage and uniform surface morphologies.