Host-Guest Chemistry Meets Electrocatalysis: Cucurbit[6]uril on a Au Surface as a Hybrid System in CO₂ Reduction

TY - JOUR

T1 - Host-Guest Chemistry Meets Electrocatalysis

T2 - Cucurbit[6]uril on a Au Surface as a Hybrid System in CO2 Reduction

AU - Wagner, Andreas

AU - Ly, Khoa H.

AU - Heidary, Nina

AU - Szabó, István

AU - Földes, Tamás

AU - Assaf, Khaleel I.

AU - Barrow, Steven J.

AU - Sokołowski, Kamil

AU - Al-Hada, Mohamed

AU - Kornienko, Nikolay

AU - Kuehnel, Moritz F.

AU - Rosta, Edina

AU - Zebger, Ingo

AU - Nau, Werner M.

AU - Scherman, Oren A.

AU - Reisner, Erwin

PY - 2020/1/3

Y1 - 2020/1/3

N2 - The rational control of forming and stabilizing reaction intermediates to guide specific reaction pathways remains to be a major challenge in electrocatalysis. In this work, we report a surface active-site engineering approach for modulating electrocatalytic CO2 reduction using the macrocycle cucurbit[6]uril (CB[6]). A pristine gold surface functionalized with CB[6] nanocavities was studied as a hybrid organic-inorganic model system that utilizes host-guest chemistry to influence the heterogeneous electrocatalytic reaction. The combination of surface-enhanced infrared absorption (SEIRA) spectroscopy and electrocatalytic experiments in conjunction with theoretical calculations supports capture and reduction of CO2 inside the hydrophobic cavity of CB[6] on the gold surface in aqueous KHCO3 at negative potentials. SEIRA spectroscopic experiments show that the decoration of gold with the supramolecular host CB[6] leads to an increased local CO2 concentration close to the metal interface. Electrocatalytic CO2 reduction on a CB[6]-coated gold electrode indicates differences in the specific interactions between CO2 reduction intermediates within and outside the CB[6] molecular cavity, illustrated by a decrease in current density from CO generation, but almost invariant H2 production compared to unfunctionalized gold. The presented methodology and mechanistic insight can guide future design of molecularly engineered catalytic environments through interfacial host-guest chemistry.

AB - The rational control of forming and stabilizing reaction intermediates to guide specific reaction pathways remains to be a major challenge in electrocatalysis. In this work, we report a surface active-site engineering approach for modulating electrocatalytic CO2 reduction using the macrocycle cucurbit[6]uril (CB[6]). A pristine gold surface functionalized with CB[6] nanocavities was studied as a hybrid organic-inorganic model system that utilizes host-guest chemistry to influence the heterogeneous electrocatalytic reaction. The combination of surface-enhanced infrared absorption (SEIRA) spectroscopy and electrocatalytic experiments in conjunction with theoretical calculations supports capture and reduction of CO2 inside the hydrophobic cavity of CB[6] on the gold surface in aqueous KHCO3 at negative potentials. SEIRA spectroscopic experiments show that the decoration of gold with the supramolecular host CB[6] leads to an increased local CO2 concentration close to the metal interface. Electrocatalytic CO2 reduction on a CB[6]-coated gold electrode indicates differences in the specific interactions between CO2 reduction intermediates within and outside the CB[6] molecular cavity, illustrated by a decrease in current density from CO generation, but almost invariant H2 production compared to unfunctionalized gold. The presented methodology and mechanistic insight can guide future design of molecularly engineered catalytic environments through interfacial host-guest chemistry.

KW - electrocatalytic CO reduction

KW - host-guest chemistry

KW - supramolecular catalysis

KW - surface active-site engineering

UR - http://www.scopus.com/inward/record.url?scp=85078919027&partnerID=8YFLogxK

U2 - 10.1021/acscatal.9b04221

DO - 10.1021/acscatal.9b04221

M3 - Article

AN - SCOPUS:85078919027

SN - 2155-5435

VL - 10

SP - 751

EP - 761

JO - ACS Catalysis

JF - ACS Catalysis

IS - 1

ER -