Achieving High-Efficient Photoelectrocatalytic Degradation of 4-Chlorophenol via Functional Reformation of Titanium-Oxo Clusters

Rational design of crystalline catalysts with superior light absorption and charge transfer for efficient photoelectrocatalytic (PEC) reaction coupled with energy recovery remains a great challenge. In this work, we elaborately construct three stable titanium-oxo clusters (TOCs, Ti₁₀Ac₆, Ti₁₀Fc₈, and Ti₁₂Fc₂Ac₄) modified with a monofunctionalized ligand (9-anthracenecarboxylic acid (Ac) or ferrocenecarboxylic acid (Fc)) and bifunctionalized ligands (Ac and Fc). They have tunable light-harvesting and charge transfer capacities and thus can serve as outstanding crystalline catalysts to achieve efficient PEC overall reaction, that is, the integration of anodic organic pollutant 4-chlorophenol (4-CP) degradation and cathodic wastewater-to-H₂ conversion. These TOCs can all exhibit very high PEC activity and degradation efficiency of 4-CP. Especially, Ti₁₂Fc₂Ac₄ decorated with bifunctionalized ligands exhibits better PEC degradation efficiency (over 99%) and H₂ generation than Ti₁₀Ac₆ and Ti₁₀Fc₈ modified with a monofunctionalized ligand. The study of the 4-CP degradation pathway and mechanism revealed that such better PEC performance of Ti₁₂Fc₂Ac₄ is probably due to its stronger interactions with the 4-CP molecule and better ^•OH radical production. This work not only presents the effective combination of organic pollutant degradation and simultaneously H₂ evolution reaction using crystalline coordination clusters as both anodic and cathodic catalyst but also develops a new PEC application for crystalline coordination compounds.