Hydroxide Ligands Cooperate with Catalytic Centers in Metal–Organic Frameworks for Efficient Photocatalytic CO₂ Reduction

Abstract

Converting CO into fuels via photochemical reactions relies on highly efficient and selective catalysts. We demonstrate that the catalytic active metal center can cooperate with neighboring hydroxide ligands to boost the photocatalytic CO reduction. Six cobalt-based metal-organic frameworks (MOFs) with different coordination environments are studied at the same reaction condition (photosensitizer, electron donor, water/organic mixed solvent, and visible light). In pure CO at 1.0 atm, the MOFs bearing μ-OH ligands neighboring the open Co centers showed CO selectivities and turnover frequencies (TOFs) up to 98.2% and 0.059 s, respectively. More importantly, their TOFs reduced only ca. 20% when the CO partial pressure was reduced to 0.1 atm, while other MOFs reduced by at least 90%. Periodic density functional theory calculations and isotope tracing experiments showed that the μ-OH ligands serve not only as strong hydrogen-bonding donors to stabilize the initial Co-CO adduct but also local proton sources to facilitate the C-O bond breaking.

Encapsulating Perovskite Quantum Dots in Iron‐Based Metal–Organic Frameworks (MOFs) for Efficient Photocatalytic CO2 Reduction

“…[1][2][3][4][5][6] In the artificial photosynthesis process,acrucial challenge is to design efficient and low-cost catalysts and photosensitizers.I nt his context, as eries of efficient photocatalysts based on earth-abundant elements,s uch as Fe, [7][8][9] Co [10][11][12][13] and Ni [14,15] have been developed. [1][2][3][4][5][6] In the artificial photosynthesis process,acrucial challenge is to design efficient and low-cost catalysts and photosensitizers.I nt his context, as eries of efficient photocatalysts based on earth-abundant elements,s uch as Fe, [7][8][9] Co [10][11][12][13] and Ni [14,15] have been developed.…”

Metal–Organic Frameworks and Their Derived Materials as Electrocatalysts and Photocatalysts for CO2 Reduction: Progress, Challenges, and Perspectives

“…The anthracene-based ligand in NNU-28n ot only serves as an effective light harvester to Zr 6 -oxo cluster through the ligand-to-metal Figure 13. [47] In their study,s ix Co-based MOFs were studied to investigatet he influence of coordination environments. b) Proposed photocatalytic reaction mechanism for CO 2 reduction to HCOO À by the Ru-based MOF.R eproduced with permission from reference [57].Copyright2 015 Royal SocietyofC hemistry.…”

Spinel‐Type Mixed Metal Sulfide NiCo2S4 for Efficient Photocatalytic Reduction of CO2 with Visible Light

“…The efficient CO 2 photoreduction systems are typically composed of several modules, such as light harvesters, electron mediator, CO 2 activators and their desired integration, to operate the reaction through a tandem manner. [24][25][26][27] Nickel and cobalt species with rich redox states have been demonstrated to be active sites of photocatalysts, which can powerfully promote the separation and transfer of light-excited charges of CO 2 photoconversion catalysis. [18,[26][27][28][29][30][31] When the reduction reaction is further coupled with the protons, reinforced performance of CO 2 photoreduction can be achieved.…”