The Electron Transport Regulation in Carbon Dots/In₂O₃ Electrocatalyst Enable 100% Selectivity for Oxygen Reduction to Hydrogen Peroxide

Abstract

Direct electrosynthesis of hydrogen peroxide (H2O2) via two‐electron pathway oxygen reduction reaction (2e− ORR) is crucially essential for a sustainable green economy. However, catalysts inevitably undergo four‐electron pathway oxygen reduction reaction (4e− ORR), resulting in low selectivity and economic benefits. The current challenge is to provide a feasible design strategy for obtaining satisfactory 2e− ORR catalysts with high selectivity. In this work, carbon dots (CDs) act as a cocatalyst to regulate the electron transport kinetics of In2O3/CDs, and the influence of CDs on the ORR pathways of In2O3/CDs is also studied. The electron transfer kinetics on In2O3/CDs composites are studied and analyzed using the transient photo‐induced voltage (TPV) technology. Combining the TPV results and kinetics analysis, it is shown that the electron transport on the In2O3 interface is obviously weakened after the addition of CDs, resulting in a high H2O2 selectivity. It is also demonstrated that CDs can effectively enhance the selectivity of H2O2, and the H2O2 selectivity of In2O3/CDs–10 is in close proximity to 100%, which is much higher than that of pure In2O3 (72%). This work will provide a new understanding and insight into addressing the challenge of low H2O2 selectivity for 2e− ORR catalysts.

Self-assembly of a heterogeneous microreactor with carbon dots embedded in Ti-MOF derived ZnIn2S4/TiO2 microcapsules for efficient CO2 photoreduction

“…Carbon dots (CDs) have both remarkable light-harvesting and electron-transfer/reservoir abilities, which may act as an important component of the microreactor. 18–24 With CDs in a microreactor system, the transportation of photogenerated electrons in the encapsulation system will become faster and more efficient. 25 CDs as electron storage containers may capture more electrons from the semiconductor catalyst and regulate the local charge distribution, thus acquiring more electrons to produce CH 4 .…”

Carbon Dots from d-Cysteine and Citric Acid Increase the Activity of the Enzyme Laccase

“…The peak at 2550 cm –1 for the S–H stretching mode of d -Cys is absent in d -CDots, confirming that d -CDots are free from nonbond d -Cys, which supports that the chiral CDot samples are purified enough. The peaks at 3450 and 2919 cm –1 are assigned to the stretching vibrations of O–H and C–H, respectively . The absorption bands located at approximately 1629 and 1393 cm –1 are attributed to the CO and C–N vibrations, respectively. , Moreover, the dwarf peak at 1159 cm –1 can be assigned to a C–S bond .…”

“…The peaks at 3450 and 2919 cm −1 are assigned to the stretching vibrations of O−H and C−H, respectively. 22 The absorption bands located at approximately 1629 and 1393 cm −1 are attributed to the C�O and C−N vibrations, respectively. 23,24 Moreover, the dwarf peak at 1159 cm −1 can be assigned to a C−S bond.…”

Recent progress in electrocatalytic selectivity in heterogeneous electro-Fenton processes

“…The electron transport on the In 2 O 3 interface was weakened after the addition of CDs, resulting in higher H 2 O 2 selectivity of In 2 O 3 /CDs-10 (near 100%) than that of pure In 2 O 3 (72%). 89 Zhang et al found that titanium-doped zinc–cobalt sulfide hollow superstructure (Ti–ZnCoS HSS) was an efficient electrocatalyst for H 2 O 2 electrosynthesis. The polymetallic composition could tailor the d-band center and binding energy with oxygen species to deliver a high selectivity of 98%, an H 2 O 2 production rate of 675 mmol h −1 g (cat.)…”