Daobin Tang

A common supporting electrolyte, tetrabutyllhexafluorophosphate ammonium (TBAPF ₆ ), exhibits unique electrochemical behavior when mixed with hole‐sacrificing agent potassium iodide (KI). In this work, a photoelectrochemical system with a sulfur‐based semiconductor Se‐CdS‐MPA photoelectrode is constructed for the mechanistic investigation of iodobutane production via KI and TBAPF ₆ . The reaction can be carried out in both half‐cells, and factors such as the catalytic medium and external stimuli impact the iodobutane production rate. The overall iodobutane yield was 176.87 mol% after 10 h in both compartments of the system. Varying alkyl iodides are prepared through the reaction of ammonium ions with different alkyl chain lengths and iodide ions. Both the conversion and product yield increase with the elongation of alkyl chain length through an electron‐transfer‐controlled mechanism. The reaction proceeds spontaneously via S _N 2 nucleophilic substitution, and the alkyl iodides are synthesized in conjunction with radical mechanisms under PEC conditions. The iodide ion also coupled with the cadmium ion from photo‐oxidative decomposition of the photoelectrode to constitute a new photocatalyst, CdI ₂ , which improves the stability and photocurrent density of the system significantly. This work put forward a clear theoretical reference for the study of PEC and chalcogenide semiconductors.

The selective C-C bond oxidation in lignin β-1 monomers through photoelectrochemistry(PEC) techniques holds practical significance. Employing CdS-based photoelectrodes and benzoin(BENZ) as the β-1 model compound, oriented adsorption regulation mechanisms of Se-doping on the products selectivity of benzaldehyde and benzoic acid were investigated. Following 24h hydrothermal reaction in a 3:1 ethanol/water mixed solvent with 5 wt% selenium doping, an alloy phase Se-CdS photoelectrode(CdS0.945Se0.055) was synthesized, exhibiting the highest supported thickness and superior adsorption on the (002) plane toward substrate. In a mercaptopropionic acid(MPA) solubilization ligand system without supporting electrolytes, Se-CdS-MPA photoelectrodes converted all BENZ into benzaldehyde and benzoic acid after 3h, with higher selectivity for benzoic acid (51.70%). The distinct product distributions with Se doping depend on different substrate adsorption mechanisms: benzaldehyde is generated via benzyl alcohol radicals when BENZ adsorbs onto Se-CdS-MPA ligand, whereas benzoic acid is yielded via benzaldehyde radicals when BENZ adsorbs onto the (002) plane of Se-CdS. In addition, the cathode cell simultaneously synthesized alkyl iodides (91.28 wt% of maximum yield) via photogenerated electrons produced by Se-doped photoelectrodes, realizing valorized transformations in both cells under organic systems. This work represents a successful attempt for controllable β-1 monomers transformation and efficient utilization of PEC organic systems.

The mechanism, substrate transformation, photoelectrodes, and configurations of photoelectrochemistry (PEC) of biomass are reviewed, different from PEC water splitting, photocatalysis, or electrocatalysis.