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?

A review on g-C3N4-based photocatalysts

Generations Yi Ma,† Xiuli Wang,† Yushuai Jia,† Xiaobo Chen,‡ Hongxian Han,*,† and Can Li*,† †State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Dalian National Laboratory for Clean Energy, 457 Zhongshan Road, Dalian 116023, China ‡Department of Chemistry, College of Arts and Sciences, University of Missouri-Kansas City, 5100 Rockhill Road, Kansas City, Missouri 64110, United States

Titanium dioxide-based nanomaterials for photocatalytic fuel generations.

The applications of copper (Cu) and Cu-based nanoparticles, which are based on the earth-abundant and inexpensive copper metal, have generated a great deal of interest in recent years, especially in the field of catalysis. The possible modification of the chemical and physical properties of these nanoparticles using different synthetic strategies and conditions and/or via postsynthetic chemical treatments has been largely responsible for the rapid growth of interest in these nanomaterials and their applications in catalysis. In addition, the design and development of novel support and/or multimetallic systems (e.g., alloys, etc.) has also made significant contributions to the field. In this comprehensive review, we report different synthetic approaches to Cu and Cu-based nanoparticles (metallic copper, copper oxides, and hybrid copper nanostructures) and copper nanoparticles immobilized into or supported on various support materials (SiO2, magnetic support materials, etc.), along with their applications i...

http://pubs.acs.org/doi/pdfplus/10.1021/acs.chemrev.5b00482

Cu and Cu-Based Nanoparticles: Synthesis and Applications in Catalysis.

Control of TiO2 crystal facets has attracted enormous interest due to the fascinating shape-dependent photocatalytic activity of this material. In this work, the effect of the ratio of {001} and {101} facets on the photocatalytic CO2-reduction performance of anatase TiO2 is reported. A new “surface heterojunction” concept is proposed on the basis of the density functional theory (DFT) calculations to explain the difference in the photocatalytic activity of TiO2 with coexposed {001} and {101} facets.

Enhanced Photocatalytic CO2-Reduction Activity of Anatase TiO2 by Coexposed {001} and {101} Facets

Electrocatalytic reduction of CO2 into multicarbon (C2+) products is a highly attractive route for CO2 utilization; however, the yield of C2+ products remains low because of the limited C2+ selectivity at high CO2 conversion rates. Here we report a fluorine-modified copper catalyst that exhibits an ultrahigh current density of 1.6 A cm−2 with a C2+ (mainly ethylene and ethanol) Faradaic efficiency of 80% for electrocatalytic CO2 reduction in a flow cell. The C2–4 selectivity reaches 85.8% at a single-pass yield of 16.5%. We show a hydrogen-assisted C–C coupling mechanism between adsorbed CHO intermediates for C2+ formation. Fluorine enhances water activation, CO adsorption and hydrogenation of adsorbed CO to CHO intermediate that can readily undergo coupling. Our findings offer an opportunity to design highly active and selective CO2 electroreduction catalysts with potential for practical application. Electrocatalytic reduction of CO2 into multicarbon (C2+) products is a highly attractive route for CO2 utilization. Now, a fluorine-modified copper catalyst is shown to achieve current densities of 1.6 A cm−2 with a C2+ Faradaic efficiency of 80% for electrocatalytic CO2 reduction in a flow cell.

Electrocatalytic reduction of CO2 to ethylene and ethanol through hydrogen-assisted C–C coupling over fluorine-modified copper

Photocatalytic and photoelectrocatalytic reduction of CO2 using heterogeneous catalysts with controlled nanostructures

National Basic Research Program of China [2010CB732303, 2013CB933100]; NSF of China [21033006]; Program for Changjiang Scholars and Innovative Research Team in University [IRT1036]

Photocatalytic Conversion of Carbon Dioxide with Water into Methane: Platinum and Copper(I) Oxide Co‐catalysts with a Core–Shell Structure

Electrocatalytic reduction of CO2 to fuels and chemicals is one of the most attractive routes for CO2 utilization. Current catalysts suffer from low faradaic efficiency of a CO2-reduction product at high current density (or reaction rate). Here, we report that a sulfur-doped indium catalyst exhibits high faradaic efficiency of formate (>85%) in a broad range of current density (25–100 mA cm−2) for electrocatalytic CO2 reduction in aqueous media. The formation rate of formate reaches 1449 μmol h−1 cm−2 with 93% faradaic efficiency, the highest value reported to date. Our studies suggest that sulfur accelerates CO2 reduction by a unique mechanism. Sulfur enhances the activation of water, forming hydrogen species that can readily react with CO2 to produce formate. The promoting effect of chalcogen modifiers can be extended to other metal catalysts. This work offers a simple and useful strategy for designing both active and selective electrocatalysts for CO2 reduction. CO2 conversion to liquid fuels provides an appealing means to remove the greenhouse gas, although it is challenging to find materials that are both active and selective. Here, authors show sulfur-doped indium to be a highly active and selective electrocatalyst that transforms CO2 into formate.

/pdf/promoting-electrocatalytic-co2-reduction-to-formate-via-73a0so0und.pdf

Promoting electrocatalytic CO2 reduction to formate via sulfur-boosting water activation on indium surfaces.

The photocatalytic reduction of carbon dioxide with water to fuels and chemicals is a longstanding challenge. This article focuses on the effects of cocatalysts and reaction modes on photocatalytic behaviors of TiO2 with an emphasis on the selectivity of photogenerated electrons for CO2 reduction in the presence of H2O, which has been overlooked in most of the published papers. Our results clarified that the reaction using H2O vapor exhibited significantly higher selectivity for CO2 reduction than that by immersing the photocatalyst into liquid H2O. We examined the effect of noble metal cocatalysts and found that the rate of CH4 formation increased in the sequence of Ag < Rh < Au < Pd < Pt, corresponding well to the increase in the efficiency of electron–hole separation. This indicates that Pt is the most effective cocatalyst to extract photogenerated electrons for CO2 reduction. The selectivity of CH4 in CO2 reduction was also enhanced by Pt. The size and loading amount of Pt affected the activity; a sma...

Shunji Xie

Papers

Electrocatalytic reduction of CO2 to ethylene and ethanol through hydrogen-assisted C–C coupling over fluorine-modified copper

Photocatalytic and photoelectrocatalytic reduction of CO2 using heterogeneous catalysts with controlled nanostructures

Photocatalytic Conversion of Carbon Dioxide with Water into Methane: Platinum and Copper(I) Oxide Co‐catalysts with a Core–Shell Structure

Promoting electrocatalytic CO2 reduction to formate via sulfur-boosting water activation on indium surfaces.

MgO- and Pt-Promoted TiO2 as an Efficient Photocatalyst for the Preferential Reduction of Carbon Dioxide in the Presence of Water