Construction of carboxyl position-controlled Z-scheme n-ZnO/p-Cu2O heterojunctions with enhanced photocatalytic property for different pollutants

Solar-based photocatalytic ozonation employing novel S-scheme ZnO/Cu2O/CuO/carbon xerogel photocatalyst: effect of pH, salinity, turbidity, and temperature on salicylic acid degradation

This paper proposes the study of a solar-based photocatalytic ozonation process for the degradation of salicylic acid (SA) using a novel S-scheme ZnO/Cu2O/CuO/carbon xerogel photocatalyst. The incorporation of CuO and Cu2O aims to enhance charge mobility through the formation of p-n heterojunctions with ZnO, whereas the carbon xerogel (XC) was selected due to its eco-friendly nature, capacity to stabilize S-scheme heterojunctions as a solid-state electron mediator, and ability to function as a reducing agent under high temperatures. The characterization of the composites demonstrates that the presence of the XC during the calcination step led to the reduction of a fraction of the CuO into Cu2O, forming a ternary semiconductor heterojunction system. In terms of photocatalysis, the XC/ZnO-CuxO 5% composite achieved the best efficiency for salicylic acid degradation, mainly due to the stabilization of the S-scheme charge transfer pathway between the ZnO/CuO/Cu2O semiconductors by the XC. The total organic carbon (TOC) removal during heterogeneous photocatalysis was 80% for the solar-based process and 68% for the visible light process, after 300 min. The solar-based photocatalytic ozonation process was highly successful regarding the degradation of SA, achieving a 75% increase in the apparent reaction rate constant when compared to heterogeneous photocatalysis. Furthermore, a 78% TOC removal was achieved after 150 min, which is half the time required by the heterogeneous photocatalysis to obtain the same result. Temperature, salinity, and turbidity had major effects on the efficiency of the photocatalytic ozonation process; the system's pH did not cause any major performance variation, which holds relevance for industrial applications.

Precise real-time quantification for photocatalytic reaction: integration of the sensitivein-situSERS sensor and high-efficiency photocatalyst

Recently,in-situsurface-enhanced Raman spectroscopy (SERS) is gradually becoming an important method for monitoring photocatalytic reaction processes, in which the quantification potential is a vital factor in determining whether this technology can be truly applied in the future. In order to improve the quantification performance ofin-situSERS and explore a precise operando Raman detection for photocatalytic reactions, an architecture of heterostructural Cu₂O/ZnO/Ag nano round brush has been designed and discussed in this work. This structure is an integration of sensitivein-situSERS sensor and high-efficiency photocatalyst, realizing real-time monitoring of photocatalytic reaction in a wide concentration range from 20 to 3 mg l^-1. The coefficient of determination between different detection methods is beyond 0.86 in this range, implying the high-precise quantification of this platform. Comprehensive analysis on structure effect, SERS performance, photocatalytic property, electric filed characteristic, etc were all systematically made and discussed in detail for this platform. This work presents a precise preliminar real-time photocatalytic monitoring usingin-situSERS detection, which is a new attempt and also meaningful reference for otherin-situanalytical technology.

A Review on Preparation and Photocatalytic Hydrogen Evolution of Core-shell Cu2O Composites

Abstract:Due to the appropriate bandgap, Cu2O has been widely studied in the field of photocatalytic hydrogen evolution. The core-shell structure is used to design the photocatalytic semiconductor material, so that...

Construction of Low-Cost Z-Scheme Heterostructure Cu2 O/PCN for Highly Selective CO2 Photoreduction to Methanol with Water Oxidation

Solar-driven CO₂ reaction with water oxidation into alcohols represents a promising approach to achieve real artificial photosynthesis. However, rapid recombination of photogenerated carriers seriously restricts the development of artificial photosynthesis. Herein, a facile method is explored to construct low-cost Z-Scheme heterostructure Cu₂ O/polymeric carbon nitride (PCN) by in situ growth of Cu₂ O hollow nanocrystal on PCN. The protective PCN layer and Z-schematic charge flow can make robust Cu₂ O/PCN photocatalysts, and the spatial separation of electrons and holes with high redox potentials of E_CB (-1.15 eV) and E_VB (1.65 eV) versus NHE can efficiently drive CO₂ photoreduction to methanol in pure water, which is further confirmed by DFT calculation. The Z-scheme heterostructure Cu₂ O/PCN exhibits a high methanol yield of 276 µmol g^-1 in 8 h with ca. 100% selectivity, much superior to that of isolated Cu₂ O and PCN, and all the reported Cu₂ O-based heterostructures. This work provides a unique strategy to efficiently and selectively promote the conversion of CO₂ and H₂ O into high-value chemicals by constructing a low-cost Z-scheme heterostructure.