Photo- and Electrocatalytic Reduction of CO2 over Metal-Organic Frameworks and Their Derived Oxides: A Correlation of the Reaction Mechanism with the Electronic Structure

Soumitra Payra; Subhasmita Ray; Ruchi Sharma; Kartick Tarafder; Paritosh Mohanty; Sounak Roy

doi:10.1021/acs.inorgchem.1c03317

Photo- and Electrocatalytic Reduction of CO₂ over Metal-Organic Frameworks and Their Derived Oxides: A Correlation of the Reaction Mechanism with the Electronic Structure

Inorg Chem. 2022 Feb 7;61(5):2476-2489. doi: 10.1021/acs.inorgchem.1c03317. Epub 2022 Jan 27.

Authors

Soumitra Payra¹, Subhasmita Ray², Ruchi Sharma³, Kartick Tarafder², Paritosh Mohanty³, Sounak Roy¹

Affiliations

¹ Department of Chemistry, Birla Institute of Technology and Science (BITS) Pilani, Hyderabad Campus, Hyderabad 500078, India.
² Department of Physics, National Institute of Technology Karnataka, Mangalore 575025, India.
³ Functional Materials Laboratory, Department of Chemistry, IIT Roorkee, Roorkee 247667, India.

PMID: 35084843
DOI: 10.1021/acs.inorgchem.1c03317

Abstract

A Ce/Ti-based bimetallic 2-aminoterephthalate metal-organic framework (MOF) was synthesized and evaluated for photocatalytic reduction of CO₂ in comparison with an isoreticular pristine monometallic Ce-terephthalate MOF. Owing to highly selective CO₂ adsorption capability, optimized band gaps, higher flux of photogenerated electron-hole pairs, and a lower rate of recombination, this material exhibited better photocatalytic reduction of CO₂ and lower hydrogen evolution compared to Ce-terephthalate. Thorough probing of the surface and electronic structure inferred that the reducibility of Ce⁴⁺ to Ce³⁺ was due to the introduction of an amine functional group into the linker, and low-lying Ti(3d) orbitals in Ce/Ti-2-aminoterephthalate facilitated the photoreduction reaction. Both the MOFs were calcined to their respective oxides of Ce_1-xTi_xO₂ and CeO₂, and the electrocatalytic reduction of CO₂ was performed over the oxidic materials. In contrast to the photocatalytic reaction mechanism, the lattice substitution of Ti in the CeO₂ fluorite cubic structure showed a better hydrogen evolution reaction and consequently, poorer electroreduction of CO₂ compared to pristine CeO₂. Density functional theory calculations of the competitive hydrogen evolution reaction on the MOF and the oxide surfaces corroborated the experimental findings.