Carbon Quantum Dot Conjugated Copper(II) Phthalocyanine Integrating BiVO₄ Semiconductor for Photocatalytic Water Oxidation

Abstract

Photocatalytic water splitting as one of the most promising strategies has attracted widespread attention to solve the energy crisis, in which water oxidation was the bottleneck because of the complex four-electron reaction process. Bismuth vanadate (BiVO 4 ), as a widely studied light-harvesting semiconductor in photocatalytic water oxidation, suffers from a low separated rate of photogenerated charge carriers and poor stability. Herein, carbon quantum dots (CQDs) and copper(II) phthalocyanine (CuPc) form tight conjugate systems by π−π electron stacking, which then coupled with BiVO 4 by a hydrothermal method to construct a water oxidation photocatalyst BiVO 4 /CQDs/CuPc. The hybrid catalyst exhibits efficient photocatalytic water oxidation activity due to the presence of a Z-scheme transfer mechanism, in which the O 2 -evolved amount for an optimal sample is about 5.1 times (371.8 μmol g −1 h −1 ) higher than that of bare BiVO 4 . The apparent quantum efficiency (AQE) in 1 h is 36.8%. Additionally, in this Z-scheme system, CuPc coupled with BiVO 4 enhances the separation efficiency of photogenerated charge carries, where CQDs play a role in the electron shuttle, promoting the electron transfer rate between CuPc and BiVO 4 . Our study demonstrates that CQDs and CuPc are introduced to couple with the inorganic semiconductor BiVO 4 to fabricate efficient ternary composite water oxidation photocatalysts.

Construction of organic–inorganic hybrid photoanodes with metal phthalocyanine complexes to improve photoelectrochemical water splitting performance

“…The FT-IR spectrum of pristine BVO shows three characteristic peaks, the peak at 476 cm À1 corresponds to the Bi-O vibrations, and the peaks at 824 and 733 cm À1 correspond to the V-O vibrations. 43,44 Compared with that of BVO, the IR spectrum of BVO/CoPc contains several peaks at 1608, 1503, 1333, 1119, and 1087 cm À1 , and the peaks located at 1608, 1503, 1119, and 1087 cm À1 correspond to the phthalocyanine skeletal vibrations, 15,45 and the peak at 1333 cm À1 corresponds to the C-NQ stretching vibrations, 46 which further proves that the BVO/CoPc photoanode has been successfully prepared. In order to explore the optical characteristics of the hybrid photoanode, the UV-vis spectrum of the sample was also recorded.…”

“…11 To eliminate these drawbacks, researchers are committed to modifying the photoanode surface with oxygen evolution catalysts (OECs), which could suppress the charge carrier recombination and accelerate the surface water oxidation kinetics. [12][13][14][15] Up to now, numerous non-noble-metalbased OECs materials have been developed on BVO photoanodes, most of which are transition metal oxides [16][17][18][19] and hydroxides. 4,[20][21][22][23] In general, these inorganic OECs are modified on the surface of BVO photoanodes by hydrothermal, immersing-annealing, and (photo)electrodeposition methods.…”

Prussian Blue Type Cocatalysts for Enhancing the Photocatalytic Water Oxidation Performance of BiVO4

“…The boosted amplitude of O 2 evolution rate for Co−Co PBA@BiVO 4 ‐10 compared to that of pure BiVO 4 is pretty high among those of reported BiVO 4 based PEC or photocatalytic systems for water oxidation (Table S1 and S2) [25–29,35–46] . O 2 production kinetic curve of Co−Co PBA@BiVO 4 ‐10 sample during 4 h displays that O 2 evolution amount always increases but rate gradually slows down (Figure 4c), which may be caused by the change of pH and decreased concentration of NaIO 3 .…”

“…[34] The boosted amplitude of O 2 evolution rate for CoÀ Co PBA@BiVO 4 -10 compared to that of pure BiVO 4 is pretty high among those of reported BiVO 4 based PEC or photocatalytic Chemistry-A European Journal systems for water oxidation (Table S1 and S2). [25][26][27][28][29][35][36][37][38][39][40][41][42][43][44][45][46] O 2 production kinetic curve of CoÀ Co PBA@BiVO 4 -10 sample during 4 h displays that O 2 evolution amount always increases but rate gradually slows down (Figure 4c), which may be caused by the change of pH and decreased concentration of NaIO 3 . As for pure BiVO 4 , the degree of the change in pH and concentration of NaIO 3 is smaller than those of the CoÀ Co PBA@BiVO 4 -10 sample due to the low photocatalytic activity, so the O 2 evolution rate has not changed too much.…”

The Journal of Physical Chemistry C Virtual Special Issue on “Energy and Catalysis in China”

“…(3) Synthesis of fine chemicals: selective reduction of nitrobenzene on iron and nitrogen cofunctionalized carbon materials or PtPdCu/Al 2 O 3 , hydrogenation of quinoline and benzoic acid on RhPt/MCM-41, hydroformylation of diisobutene on CoFe alloy catalysts, and selective hydrogenation of cinnamaldehyde to cinnamyl alcohol on Pt@Fe-CeO 2 catalysts or Pt/TiO 2 . Photocatalysis can directly convert solar energy into chemical energy, and two important photocatalytic reactions are included in this VSI: photocatalytic water splitting on Au nanoparticles embedded in g -C 3 N 4 , BiVO 4 , Ta 3 N 5 , SnNb 2 O 6 nanoplates, silicon material, MoO 3 –ZnIn 2 S 4 , carbon nitride, NiFe metal–organic framework (MOF) and cobaloxime-modified Ti-doped hematite, and photocatalytic CO 2 conversion on α-Fe 2 O 3 /CdS heterostructures, CdSe/CdSe x S 1– x /CdS alloyed quantum dots/TiO 2 , AgTaO 3 , perylene diimide/graphene- g -C 3 N 4 , P-doped ZnIn 2 S 4 , MCo 2 O 4−δ (M = Zn, Ni, Cu), and PtRu/TiO 2 . A few other photocatalytic reactions, such as the selective oxidation of cyclohexane to cyclohexanone on In 2 O 3 /N-doped TiO 2 , the reduction of aromatic nitro compounds on Ag/Ag x S, and NO removal on Ba-doped BiOBr, are also discussed.…”