Au-Modulated Z-Scheme CuPc/BiVO₄ Nanosheet Heterojunctions toward Efficient CO₂ Conversion under Wide-Visible-Light Irradiation

Abstract

Unraveling the sluggish charge separation, insufficient catalytic sites, and limited visible-light absorption for Z-scheme heterojunction photocatalysts still remains a great challenge toward CO2 conversion. Herein, ultrafine Au-modulated copper phthalocyanine/BiVO4 nanosheet heterojunctions (CuPc/Au-BVNS) with wide-visible-light responses have been successfully fabricated as efficient photocatalysts for CO2 conversion to CO, achieving 9-time and 35-time photoactivity improvement compared to pristine BVNS (ca. 5 nm) and the previously reported BiVO4 nanoflake (ca. 15 nm), respectively. The exceptional photoactivity is mainly attributed to the ultrafine Au interfacial modulation, which is well capable of inducing the directional electron migration of BVNS and the highly dispersed CuPc assembly with the increased loading amount, synergistically strengthening the Z-scheme charge transfer and separation mainly based on the surface photovoltage spectroscopy assisted with the monochromatic beam and electron paramagnetic resonance technique. Moreover, the in situ diffuse reflectance infrared Fourier transform spectroscopy, CO2 temperature-programmed desorption measurement, and electrochemical results demonstrate that the central metal Cu2+ in the high-dispersion CuPc exhibits potential catalytic functions for CO2 reduction, much superior to other metals in MPc (M = Co and Ni)-modified ones. This work highlights the importance of strengthening artificial Z-scheme charge transfer and provides new strategies for designing BiVO4-based heterojunctions by controllably assembling MPc toward efficient solar-driven CO2 conversion.

Improved Photocatalytic Activities of g-C3N4 Nanosheets by B Doping and Ru-Oxo Cluster Modification for CO2 Conversion

“…To deeply investigate the change of the adsorbed reaction molecules on the surface of photocatalysts during the photocatalytic CO 2 reduction process, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) in the presence of CO 2 and H 2 O vapor was performed. As shown in Figure 4a,b, the adsorption peaks in the region from 2200 to 2400 cm −1 are assigned to the asymmetric stretching vibration of CO 2 molecules, 37,38 and the adsorption peaks for the surface −OH stretching of H 2 O are observed in the range of 3500−3800 cm −1 . It is obvious that 2Mn-COS-BCN and 2Ru-COS-BCN show much stronger H 2 O adsorption compared with pristine BCN in the dark, while no obvious change could be observed on CO 2 adsorption.…”

Porphyrins and phthalocyanines as biomimetic tools for photocatalytic H2production and CO2reduction

“…Very recently, the further improved conversion efficiency of CO 2 to CO has been achieved by CuPc/Au-BVNS heterojunctions, which exhibit a 9-time and 35-time increase in photoactivity compared to pristine BVNS and the BiVO 4 nanoflake, respectively. 330 The authors attributed this success to the use of Au nanoparticles as an interfacial modulator, which improved electron transfer directionality in BVNS to CuPc, as well as increased CuPc loading amounts due to a superior interaction between AuNP and the N-atom of the Pc macrocycle. Indeed, as compared to the previously reported H-bond interfacial interaction, the Au nanoparticle had a better connection with the N-atom of the MPc ligand, resulting in a faster Z-scheme charge-transfer mechanism.…”

Interface Modulation of FePc/Porous Ti(HPO4)2 Z‐Scheme Heterojunctions with Ultrafine Ag for Efficiently Photocatalytic CO Oxidation

“…The infrared absorption bands located at 550–620 and 970–1250 cm −1 , respectively, corresponding to the stretching vibration of Ti–O structure and PO 4 3− group, are observed on pristine TiP NS. [ 34,35 ] There is no obvious change after Ag modification, while several peaks ranging from 1400 to 1800 cm −1 are detected on FePc/TiP NS heterojunction, which are assigned to the vibrations of phthalocyanine skeletal and center metal–ligand, respectively, [ 36 ] proving the successful integration of FePc and TiP NS. Importantly, it is noticed that the stretching vibration peak attributed to the C=N bond of the ligand of FePc over 4FePc/1.5Ag/TiP NS heterojunction has a slightly positive shift, compared with that of FePc/TiP NS one, implying the chemical interactions between Ag and FePc.…”