Nanoscale characterization of Co and Co-B catalytic coatings before and after catalytic tests for the sodium borohydride hydrolysis

Nanoscale cha ac e iza ion o Co and Co-B ca aly ic coa ings be o e and a e ca aly ic es s o he sodium bo ohyd ide hyd olysis Au ho s: Ana M Bel án (1), M Paladini (1), V Godinho (1), G.M. A zac (1), M.C. Jimenez de Ha o (1), A Fe nández (1) 1. Ins i u o de Ciencia de Ma e iales de Se illa, (CSIC - Uni . Se illa), Se illa, SPAIN DOI: 10.1002/9783527808465.EMC2016.5347 Co esponding email: [email p o ec ed] Keywo ds: Co ca alys s, Hyd ogen s o age, STEM, EELS, ca aly ic coa ings, sodium bo ohyd ide The use o hyd ogen as a po en ial u u e ene gy ca ie is limi ed due o he p oblems o i s s o age. Hyd olysis o hyd ogen s o age ma e ials such as sodium bo ohyd ide (NaBH4, SB) has been one o he mos in es iga ed app oaches o hyd ogen gene a ion. SB is s able in d y ai and combines ligh weigh wi h high hyd ogen con en (10.8 w %). NaBH4 + 2H2O → 4H2 + NaBO2 (1) Al hough spon aneous, he SB hyd olysis ( eac ion 1) needs ca alys s o occu a app eciable a es. Co has demons a ed o be a good choice because i s comp omise be ween ac i i y and cos . Howe e , i s majo d awback is ela ed o s abili y: hese ma e ials deac i a e upon cycling. Despi e he g ea numbe o wo ks epo ing Co and Co-B based ca alys s, he na u e o he ac i e phase and deac i a ion mechanisms a e s ill unde in ense discussion. We ha e ecen ly epo ed he p epa a ion o suppo ed Co me allic ca alys s as hin ilms by magne on spu e ing o sodium bo ohyd ide hyd olysis [1]. Magne on spu e ing is a e y e sa ile echnique used in his wo k o ab ica e Co and CoB ca aly ic coa ings unde di e en deposi ion condi ions and suppo ed on di e en subs a es (i.e. silicon and polyme ic memb anes). In his wo k we ha e been able o s udy by elec on mic oscopy he ca aly ic coa ings as g own on he wi es o he polyme ic memb anes. The s uc u al and composi ional cha ac e iza ion by SEM and (S)TEM echniques has been pe o med be o e and a e he ca aly ic es s (19 w % SB in NaOH 4 w %, 90 min eac ion ime). Fig. 1 and 2 show he SEM mo phology o a Co hin ilm on he polyme ic memb ane be o e and a e he ca aly ic es , espec i ely, showing he g ow h o a new laye on o he ca alys s upon ope a ion. Fu he nano-analysis o he s uc u e and composi ional dis ibu ion ha e been pe o med by (S)TEM echniques coupled o EELS. They also e eal he o ma ion o ibe /nano lake-like nanos uc u es on o he ca aly ic coa ings (Fig. 3 and Fig. 4). Composi ional analysis ha e poin ed ou he o ma ion o Co-bo a es and mos likely cobal oxide/hyd oxide nano lakes (i.e. CoO(OH)) which could be he o igin o he leaching and deac i a ion mechanisms o he Co-based ca alys s o he in es iga ed eac ion. [1] Paladini, M. e al. Applied Ca alysis B-En i onmen al 2014, 158, 400-409. This wo k was suppo ed by he Spanish MINECO (p ojec CTQ2012-32519 and CTQ2015-65918), CONSOLIDER FUNCOAT+ (MAT2015-69035-REDC), Jun a de Andalucía (PE2012-TEP862) and CSIC (PIE201460E018). The au ho s also acknowledge he Labo a o y o Nanoscopies and Spec oscopies (LANE) a he ICMS o he TEM acili ies and I. Rosa o he TEM samples p epa a ion. AMB hanks o Talen -Hub P og am unded by he Jun a de Andalucía and he Eu opean Commission unde he Co- unding o he 7 hF amewo k P og am in he People P og am (Ma ie Cu ie Special Ac ion). 822 Acknowledgemen s: Re e ences: SEM image o a Co- hin ilm on polyme ic memb ane be o e he ca aly ic es . SEM image o a Co- hin ilm on polyme ic memb ane a e he ca aly ic es TEM image o a Co hin ilm suppo ed on polyme ic memb ane a e he ca aly ic es . STEM image o a Co hin ilm suppo ed on polyme ic memb ane a e he ca aly ic es . 823