Nanoconfined self-assembly on a grafted graphitic surface under electrochemical control

Figure S1: a) First two voltammetric cycles of HOPG in 2 mM 3,5-TBD + 50 mM HCl. The first scan (blue trace) shows an irreversible reduction peak at E = -96 mV vs RHE. This peak is assigned to the reduction of the 3,5-TBD cations forming the corresponding radicals that immediately graft to the graphitic surface.1 The second cycle (red trace) however, displays a featureless curve in the same potential regime. The disappearance of the well-defined reduction peak in the subsequent cycle is the result of the formation of a non-conductive grafted film at the interface that inhibits the electron transfer from the electrode surface to the 3,5-TBD cations; b) High resolution EC-STM images of HOPG surface covalently grafted by 3,5-TBD, substrate potential E = +147 mV vs RHE, Ub = -179 mV, It = 0.2 nA.

Figure S1: a) First two voltammetric cycles of HOPG in 2 mM 3,5-TBD + 50 mM HCl.The first scan (blue trace) shows an irreversible reduction peak at E = -96 mV vs RHE.This peak is assigned to the reduction of the 3,5-TBD cations forming the corresponding radicals that immediately graft to the graphitic surface. 1 The second cycle (red trace) however, displays a featureless curve in the same potential regime.The disappearance of the well-defined reduction peak in the subsequent cycle is the result of the formation of a non-conductive grafted film at the interface that inhibits the electron transfer from the electrode surface to the 3,5-TBD cations; b) High resolution EC-STM images of HOPG surface covalently grafted by 3,5-TBD, substrate potential E = +147 mV vs RHE, Ub = -179 mV, It = 0.2 nA.Electronic Supplementary Material (ESI) for Nanoscale.This journal is © The Royal Society of Chemistry 2016

Figure S2 :
Figure S2: Multiple CV cycling on 3,5-TBD grafted HOPG showing the consistency of the onset of both OER and HER.

Figure S3 :
Figure S3: CVs of HOPG electrode in contact with 50 mM HCl (black curve) and 0.1 mM DBV + 50 mM HCl (red curve).The presence of DBV molecules leads to the appearance of two reduction peaks at E1 = -280 mV and E2 = -450 mV vs RHE that are assigned to the stepwise reduction from dicationic DBV 2+ to the corresponding radical monocationic DBV + and uncharged DBV 0 species, respectively.

Figure S4 :
Figure S4: Structural correlation between the DBV + layer in the dimer phase and the underlying HOPG lattice; a) ECSTM image of the molecule covered HOPG: E = -340 mV, Ub = +200 mV, It = 0.1 nA; b) HOPG lattice underneath after the removal of the molecule: E = -340 mV vs RHE, Ub = +10 mV, It = 2.0 nA; c) superposition of panels a and b; d) tentative model of the dimer phase forming on hexagonal HOPG surface including the unit cell is proposed with the lattice constants of | 2 ⃗⃗⃗⃗ | = 2.6 ± 0.4  and | 2 ⃗⃗⃗⃗ | = 1.6 ± 0.4 , respectively, enclosing an angle of  = 60 ± 4 0 .

Figure S5 :
Figure S5: Structural correlation between the DBV 0 layer in the stacking phase and the underlying HOPG lattice, a) EC-STM image of the molecule covered HOPG: E = -510 mV vs RHE, Ub = +350 mV, It = 0.2 nA; b) EC-STM image of the HOPG lattice underneath after the removal of the molecule: E = -510 mV vs RHE, Ub = +20 mV, It = 1.8 nA; c) superposition of panels a and b; d) tentative model of the stacking phase forming on hexagonal HOPG surface.The unit cell of the DBV 0 adlayer is proposed with the lattice constants of | 2 ⃗⃗⃗⃗ | = 0.6 ± 0.4  and | 2 ⃗⃗⃗⃗ | = 2.5 ± 0.4 , respectively, enclosing an angle of  = 59 ± 4 0

Figure S6 :
Figure S6: Dynamics of phase transition from the stacking phase to the dimer phase within nanocorrals: Ub = +120mV, It = 0.2 nA