Linking Fundamentals and Devices: Evaluating Low Pt Ag Nanocatalysts in Three Electrode Systems and Operating Glycerol AEM Electrolyzers

Electro-oxidizingglycerol(GlOH)insteadofwater at the anode of an electrolyzer can lower the thermodynamic thresholdpotential by∼1Vand simultaneously produce high value-addedproducts andgreenH2 at the cathode.Herein, we reporttheuseofAgnanoparticleswhosesurfacesareenrichedwith low loadings of Pt (0.3−6.9 mol%) for the GlOH electro oxidation reaction (GEOR). The optimized Pt(0.5%)Ag/C catalyst delivers∼50%of thegeometric areanormalized-activity of commercial Pt/CforGEORin0.5MNaOH+1MGlOH, whileusingabout140times lessPt.Thisremarkableperformance originatesfromthesynergybetweenPtandAg:Ptsitesadsorband initiate glycerol oxidation, while Ag sites provide oxygenated species that sustainthereactionandsteer theproduct selectivity. Potential-dependent selectivitywasobserved: below0.9VvsRHE, glycerateand lactatedominate,whereas above0.9V,C−C scissionyieldsglycolateandformate,withrelativelylowcompleteoxidationtocarbonate.Device-level tests inananionexchange membrane(AEM)electrolyzercorroboratehalf-cell trends.AgPt/CsustainscurrentdensitiescomparabletoPt/Cbutfavorsearlier formationof tartronateandhigherglycerateproduction, confirmingthat thebimetallicinterfacemodulates thereactionpathways. Bothdevicesalsoshowlactate, i.e., theproductcomingfromacombinationofanelectrochemical andachemical transformation. Thecombinationof (i)drastically reducednoble-metal content, (ii)highactivityatpotentialswell belowtheoxygen-evolution region, (iii)tunableco-productionofC3andC2oxygenates, and(iv)cooperativePt−Agsynergy,positionsPt-decoratedAgasa cost-effectiveanodeplatformforpairedGlOHelectro-reformingandgreenH2generation.Besides,weshowedherethatthecatalysts arepromisingforothersmallorganicmoleculesandthattheresultsinthree-electrodeelectrochemicalcells,despitesomelimitations, helppredictactivityandselectivitytrends for realdevices.