As a fascinating conjugated polymer, graphitic carbon nitride (g-C3N4) has become a new research hotspot and drawn broad interdisciplinary attention as a metal-free and visible-light-responsive photocatalyst in the arena of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability, and “earth-abundant” nature. This critical review summarizes a panorama of the latest progress related to the design and construction of pristine g-C3N4 and g-C3N4-based nanocomposites, including (1) nanoarchitecture design of bare g-C3N4, such as hard and soft templating approaches, supramolecular preorganization assembly, exfoliation, and template-free synthesis routes, (2) functionalization of g-C3N4 at an atomic level (elemental doping) and molecular level (copolymerization), and (3) modification of g-C3N4 with well-matched energy levels of another semiconductor or a metal as a cocatalyst to form heterojunction nanostructures. The constructi...

Graphitic Carbon Nitride (g-C3N4)-Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer To Achieving Sustainability?

Engineering photocatalytic materials for renewable energy generation and environmental decontamination has always been a very exciting prospect to counter the global energy demands and pollution challenges. Graphitic carbon nitride (g-C 3 N 4 ), a polymeric, metal-free semiconductor with a mild band gap (2.7 eV) has become hot-spot in various scientific exploits such as environmental pollution mitigation, energy generation and storage, organic synthesis, sensors, etc. These applications exploit the interesting properties of g-C 3 N 4 such as good visible light absorption, graphene-like structure, good thermal and chemical stability and photocatalytic properties. In this review we begin with an overview of the fundamental aspects of photocatalysis as a pollution remediation strategy. This is followed by an introduction to graphitic carbon nitride as a photocatalyst, preparation strategies and its properties. Subsequently, a comprehensive and critical discussion of the various most recent developments towards enhancing the visible light photocatalytic properties of g-C 3 N 4 for pollution alleviation, selected results and important photocatalytic degradation mechanisms, is given. Summary remarks and future perspective conclude the review.

Graphitic carbon nitride (g-C3N4) nanocomposites: A new and exciting generation of visible light driven photocatalysts for environmental pollution remediation

Surface reaction kinetics and bulk charge separation are both critical to the efficiency of solar water splitting. In addition to the well-documented surface catalytic effect, the promotion of bulk charge separation upon loading of cocatalysts has rarely been reported. This paper describes the synergetic enhancement of surface reaction kinetics and bulk charge separation by introducing discrete nanoisland p-type Co3O4 cocatalysts onto n-type BiVO4, forming a p–n Co3O4/BiVO4 heterojunction with an internal electric field to facilitate charge transport. Being highly dispersed on the surface of photoanodes, the nanoisland cocatalysts could suppress the formation of recombination centers at the photoanode/cocatalyst interface. This cocatalyst-loading method achieved a charge separation efficiency of up to 77% in the bulk and 47% on the surface of catalysts. An AM 1.5G photocurrent of 2.71 mA/cm2 at 1.23 V versus the reversible hydrogen electrode for water oxidation was obtained, which is the highest photocurr...

Enhanced Surface Reaction Kinetics and Charge Separation of p-n Heterojunction Co3O4/BiVO4 Photoanodes.

A review on TiO 2 -based Z-scheme photocatalysts

Bismuth vanadate (BiVO4) is a promising visible-light driven semiconductor photocatalyst with various benefits such as low production cost, low toxicity, high photostability, resistance to photo-corrosion and narrow band gap with a good response to visible-light excite. However, the fast recombination of photoinduced charge carriers restricts their photocatalytic activity. In the past decades, many attempts were adopted to enhance the photocatalytic activity of BiVO4. Significant advances in understanding the fundamental issues and the development of an efficient photocatalyst have been made in current years. In this review, we have provided a comprehensive overview of the latest progress on the morphology control and growth mechanism of BiVO4 micro/nano-structures, doping with metal and non-metal elements and semiconductor coupling along with some highlights in the photodegradation of organic pollutants under visible-light illumination. This review may benefit the researchers and engineers in the arena of material chemistry for designing new BiVO4 based photocatalysts with low production cost and high efficiency.

A review on BiVO4 photocatalyst: Activity enhancement methods for solar photocatalytic applications

Bi0.96Sr0.04Fe0.98−xMnxCo0.02O3 (BSFMxCO, x = 0.00–0.05) thin films with ferroelectric properties were successfully prepared by chemical solution deposition (CSD). It is found that BSFMxCO has a stable trigonal structure. The conversion from Fe3+ to Fe2+ inhibiting Mn3+ and the synergistic effects of Mn3+ and Co3+ reduce the oxygen vacancies, which prevents the formation of defect complexes. The results show that the leakage current of BSFM0.04CO is dropped to 0.011 A/cm2. Simultaneously, the weakened grain boundaries resistance and the pinning effect by doping Mn3+ reduce the built-in electric field effectively, which enhances the polarization reversal current and the capacitance. Under the applied electric field, we have obtained the intrinsic residual polarization value of 151 μC/cm2, thanks to the easily reversed domains of BSFM0.04CO and the enhanced intrinsic polarization. Therefore, ion doping can reduce oxygen vacancies and the grain boundary resistance. As a result, the intrinsic ferroelectricity in BiFeO3 is enhanced by the improvement of intrinsic polarization.

Oxygen vacancy and grain boundary resistance regulate the intrinsic ferroelectric properties of Bi0.96Sr0.04Fe0.98−xMnxCo0.02O3 thin film

Structural, electrical, and magnetic properties of multiferroic Bi1−xGdxFe0.97Co0.03O3 thin films

Pure orthorhombic phase Bi2WO6 powders were synthesized by a microwave hydrothermal method in the absence of surfactants and templates, using Bi(NO3)3·5H2O and Na2WO4·2H2O as raw materials. Photocatalytic properties of the samples prepared at different reaction temperatures were also studied with Rhodamine B (RhB) solution as the target catabolite under visible light. The results indicate that flower-like Bi2WO6 powders can be obtained by controlling the microwave reaction temperatures in the absence of any additives. The growth of flower-like Bi2WO6 powders is a multistage layer assembly process, in which the flower-like Bi2WO6 self-assembling with the uniform size about 2 μm is synthesized at 180 °C. At the same time, the photocatalytic reaction rate constant (k) gets up to 0.04167/min and the degradation rate of RhB solution is more than 96 % after being irradiated under visible light for 70 min.

Huijun Ren

Papers

Oxygen vacancy and grain boundary resistance regulate the intrinsic ferroelectric properties of Bi0.96Sr0.04Fe0.98−xMnxCo0.02O3 thin film

Structural, electrical, and magnetic properties of multiferroic Bi1−xGdxFe0.97Co0.03O3 thin films

Growth mechanism and photocatalytic properties of flower-like Bi2WO6 powders synthesized by a microwave hydrothermal method

Resistive switching behavior and improved multiferroic properties of Bi0.9Er0.1Fe0.98Co0.02O3/Co1-xMnxFe2O4 bilayered thin films

Comparative study on multiferroic (Bi0.9RE0.1)(Fe0.97Co0.03)O3−δ (RE=Ce and Ho) thin films: Structural, electrical and optical properties