Construction of Highly Active and Selective Polydopamine Modified Hollow ZnO/Co₃O₄ p-n Heterojunction Catalyst for Photocatalytic CO₂ Reduction

Abstract

The facile synthesis of low-cost, eco-friendly photocatalysts with high charge separation efficiency and CO2 adsorption capacity for efficient photocatalytic CO2 reduction remains a challenge. Herein, a hollow structured p-n heterojunction catalyst, polydopamine (PDA)-ZnO/Co3O4, was successfully synthesized by pyrolyzing bimetallic ZnCo-ZIFs, followed by modification with PDA. Through optimizing the Zn/Co ratio, a high separation efficiency of the photogenerated electron–hole pairs has been achieved. Furthermore, by tuning the content of PDA on the surface of ZnO/Co3O4, the adsorption capacity of CO2 can be maximized. Consequently, PDA15/ZnO/Co3O4 showed a CO production rate of 537.5 μmol/g/h with a CO selectivity of 97.7% without using the photosensitizer and additional sacrificial agent. Band structure based on results of X-ray photoelectron spectroscopy, photoelectrochemical characterization, as well as density functional theory calculation was used to propose a plausible mechanism for photocatalytic CO2 reduction on the PDA15/ZnO/Co3O4. The present study provides an effective approach to fabricate highly efficient photocatalysts based on semiconducting metal oxides for CO2 reduction with remarkable abilities of absorbing lights, separating charge carriers, and adsorbing CO2.

Integrated S‐Scheme Heterojunction of Amine‐Functionalized 1D CdSe Nanorods Anchoring on Ultrathin 2D SnNb2O6 Nanosheets for Robust Solar‐Driven CO2 Conversion

“…Based on the previous literature, the E CB should be ≈0.1 V above the V fb values of n‐type semiconductors. [ 60,61 ] Therefore, the E CB of SNO and that of CdSe–DET are −1.07 and −0.31 V (vs NHE), respectively. Then the E VB of SNO and that of CdSe–DET were respectively calculated to be 1.37 and 1.58 V using the formula .…”

“…Based on the previous literature, the E CB should be %0.1 V above the V fb values of n-type semiconductors. [60,61] Therefore, the E CB of SNO and that of CdSe-DET are À1.07 and À0.31 V (vs NHE), respectively.…”

Boosting light-driven CO2 reduction into solar fuels: Mainstream avenues for engineering ZnO-based photocatalysts

“…The coupling of two different SCs photocatalysts with staggering energy band structure, i.e., type-II heterostructure, is the most favorable one, which provides spatial charge carrier separation, thus affording enhanced photocatalytic activity. Li and co-researcher successfully prepared a polydopamine loaded hollow ZnO/Co 3 O 4 p-n heterostructure photocatalyst using pyrolyzing bimetallic Zn/Co-ZIFs towards CO 2 photoreduction in the presence of dimethylformamide (DMF)/H 2 O mixture solution (Li et al, 2020). The hybrid photocatalyst provides 1.4 times increase in CO 2 reduction performance, exhibiting a CO yield of 537.5 μmol g − 1 h − 1 with 97.7% CO selectivity.…”

Fine-Tuning the Metal Oxo Cluster Composition and Phase Structure of Ni/Ti Bimetallic MOFs for Efficient CO2 Reduction

“…However, the high energy barrier needs to be conquered because of the high overpotential of CO 2 /CO 2 – conversion, and efficient photocatalysts are necessary to drive the CO 2 conversion under mild condition. Metal oxides, − precious metals, − and other kinds of photocatalysts have been reported for the CO 2 conversion. Specially, metal–organic frameworks (MOFs), consisting of metal oxo clusters and organic ligands, have attracted wide attention due to their high specific surface areas, abundant pore channels, and open metal active sites as well as flexible structures and adjusted components.…”