TY - JOUR
T1 - Synthesis and characterization of structured interfaces for hydrogen generation. Study of an N,N′-dialkyl-4,4′-bipyridinium redox polymer/palladium catalyst system
AU - Bruce, James A.
AU - Murahashi, Toshiaki
AU - Wrighton, Mark S.
PY - 1982
Y1 - 1982
N2 - Structured interfaces for H2 evolution have been synthesized and characterized. The substrates studied include W, Pt, and p-Si functionalized with N,N′-bis[3-(trimethoxysilyl)propyl]-4,4′-bipyridinium dibromide, I, to give polymeric quantities of a surface-confined N,N′-dialkyl-4,4′-bipyridinium (PQ2+) redox system, [(PQ2+)n]surf. (0.5 × 10-8-5 × 10-8 mol/cm2) with an Eo′ of -0.55 ± 0.05 V vs. SCE, in aqueous electrolyte solution. Incorporation of Pd(0) (<5 × 10-8 mol/cm2) into the substrate/[(PQ2+)n]surf system leads to improvement of H2-evolution kinetics for the W and p-Si electrodes. Various procedures have been used to prepare interfaces such as (i) substrate/Pd(0)/[(PQ2+)n]surf where Pd(0) coats the substrate and the [(PQ2+)n]surf is an overlayer, (ii) substrate/ [(PQ2+)n/Pd(0)]surf where the Pd(0) is only on the outermost surface, (iii) substrate/[(PQ2+-Pd(0))n]surf where the Pd(0) is dispersed throughout the polymer overlayer, and (iv) substrate/[(PQ2+)n/Pd(0)/(PQ2+) n]surf where the Pd(0) is sandwiched between two layers of polymer. Cathodes having no Pd(0) at the substrate/ [(PQ2+)n]surf interface equilibrate with H2O/H2 only via the [(PQ2+/·+)n]surf redox couple, whereas Pd(0) in direct contact with the substrate can equilibrate the substrate with H2O/H2. Interface structures have been synthesized by deliberate electrochemical procedures and have been confirmed by Auger depth profile analyses. Current-voltage properties for the cathodes have been used to correlate structure with the H2-evolution mechanism. Heavy metal impurity ions such as Hg2+ and Pb2+ have been identified as an important source of deactivation of the catalytic activity of Pd(0).
AB - Structured interfaces for H2 evolution have been synthesized and characterized. The substrates studied include W, Pt, and p-Si functionalized with N,N′-bis[3-(trimethoxysilyl)propyl]-4,4′-bipyridinium dibromide, I, to give polymeric quantities of a surface-confined N,N′-dialkyl-4,4′-bipyridinium (PQ2+) redox system, [(PQ2+)n]surf. (0.5 × 10-8-5 × 10-8 mol/cm2) with an Eo′ of -0.55 ± 0.05 V vs. SCE, in aqueous electrolyte solution. Incorporation of Pd(0) (<5 × 10-8 mol/cm2) into the substrate/[(PQ2+)n]surf system leads to improvement of H2-evolution kinetics for the W and p-Si electrodes. Various procedures have been used to prepare interfaces such as (i) substrate/Pd(0)/[(PQ2+)n]surf where Pd(0) coats the substrate and the [(PQ2+)n]surf is an overlayer, (ii) substrate/ [(PQ2+)n/Pd(0)]surf where the Pd(0) is only on the outermost surface, (iii) substrate/[(PQ2+-Pd(0))n]surf where the Pd(0) is dispersed throughout the polymer overlayer, and (iv) substrate/[(PQ2+)n/Pd(0)/(PQ2+) n]surf where the Pd(0) is sandwiched between two layers of polymer. Cathodes having no Pd(0) at the substrate/ [(PQ2+)n]surf interface equilibrate with H2O/H2 only via the [(PQ2+/·+)n]surf redox couple, whereas Pd(0) in direct contact with the substrate can equilibrate the substrate with H2O/H2. Interface structures have been synthesized by deliberate electrochemical procedures and have been confirmed by Auger depth profile analyses. Current-voltage properties for the cathodes have been used to correlate structure with the H2-evolution mechanism. Heavy metal impurity ions such as Hg2+ and Pb2+ have been identified as an important source of deactivation of the catalytic activity of Pd(0).
UR - http://www.scopus.com/inward/record.url?scp=0000247221&partnerID=8YFLogxK
U2 - 10.1021/j100206a018
DO - 10.1021/j100206a018
M3 - Article
AN - SCOPUS:0000247221
SN - 0022-3654
VL - 86
SP - 1552
EP - 1563
JO - Journal of Physical Chemistry
JF - Journal of Physical Chemistry
IS - 9
ER -