CO Reactant Research Articles

The Pt-Pd alloy catalyst and enhanced catalytic activity for diesel oxidation

By use of a Pt-Pd alloy colloid solution, a Pt(1.0 wt%)-Pd(0.5 wt%) alloy catalyst was prepared on SiO2 support, and the supported Pt-Pd nanoparticles were verified to be highly alloyed and finely dispersed by energy dispersive X-ray spectroscopy (EDS), scanning transmission electron microscope (STEM), and CO adsorption. Under simulated diesel exhaust atmosphere, this Pt-Pd alloy catalyst exhibited a higher catalytic activity than the conventional Pt-Pd catalyst prepared by use of the common Pt and Pd precursors of Pt(NH3)2(NO2)2 and Pd(NO3)2 solutions. The characterization results of X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption of oxygen (TPD-O2) revealed that the Pt and Pd atoms of the Pt-Pd alloy catalyst were apt to be more metallic state, and the O2 adsorption and activation were facilitated significantly. Even at low temperature, there are more activated oxygen species available, and the surface of the Pt-Pd alloy catalyst gets more frequently refreshed for subsequent adsorption and activation for the CO and C3H6 reactants. The above effects resulted from the Pt-Pd alloying together with the high Pt-Pd dispersion of the supported Pt-Pd particles highly promoted the catalytic activity of the Pt-Pd alloy catalyst for diesel oxidation.

Supported mesoporous Cu/CeO2-δ catalyst for CO2 reverse water–gas shift reaction to syngas

The design and development of a high performance hydrogenation catalyst is an important challenge in the utilization of CO2 as resources. The catalytic performances of the supported catalyst can be effectively improved through the interaction between the active components and the support materials. The obtained results demonstrated that the oxygen vacancies and active Cu0 species as active sites can be formed in the Cu/CeO2-δ catalysts by the H2 reduction at 400 °C. The synergistic effect of the surface oxygen vacancies and active Cu0 species, and Cu0–CeO2-δ interface structure enhanced catalytic activity of the supported xCu/CeO2-δ catalysts. The electronic effect between Cu and Ce species boosted the adsorption and activation performances of the reactant CO2 and H2 molecules on the corresponding Cu/CeO2-δ catalyst. The Cu/CeO2-δ catalyst with the Cu loading of 8.0 wt% exhibited the highest CO2 conversion rate in the RWGS reaction, reaching 1.38 mmol·gcat−1 min−1 at 400 °C. Its excellent catalytic performance in the RWGS reaction was related to the complete synergistic interaction between the active species via Ce3+-□-Cu0 (□: oxygen vacancy). The Cu/CeO2-δ composite material is a superior catalyst for the RWGS reaction because of its high CO2 conversion and 100% CO selectivity.

Tailoring of Hydrotalcite-Derived Cu-Based Catalysts for CO2 Hydrogenation to Methanol

Ternary CuxZnyAlz catalysts were prepared using the hydrotalcite (HT) method. The influence of the atomic x:y:z ratio on the physico-chemical and catalytic properties under CO2 hydrogenation conditions was probed. The characterization data of the investigated catalysts were obtained by XRF, XRD, BET, TPR, CO2-TPD, N2O chemisorption, SEM, and TEM techniques. In the “dried” catalyst, the typical structure of a hydrotalcite phase was observed. Although the calcination and subsequent reduction treatments determined a clear loss of the hydrotalcite structure, the pristine phase addressed the achievement of peculiar physico-chemical properties, also affecting the catalytic activity. Textural and surface effects induced by the zinc concentration conferred a very interesting catalyst performance, with a methanol space time yield (STY) higher than that of commercial systems operated under the same experimental conditions. The peculiar behavior of the hydrotalcite-like samples was related to a high dispersion of the active phase, with metallic copper sites homogeneously distributed among the oxide species, thereby ensuring a suitable activation of H2 and CO2 reactants for a superior methanol production.

Testing a Silver Nanowire Catalyst for the Selective CO₂ Reduction in a Gas Diffusion Electrode Half-cell Setup Enabling High Mass Transport Conditions.

In this work, we discuss the application of a gas diffusion electrode (GDE) setup for benchmarking electrocatalysts for the reductive conversion of CO₂ (CO₂ RR: CO₂ reduction reaction). Applying a silver nanowire (Ag-NW) based catalyst, it is demonstrated that in the GDE setup conditions can be reached, which are relevant for the industrial conversion of CO₂ to CO. This reaction is part of the so-called 'Rheticus' process that uses the CO for the subsequent production of butanol and hexanol based on a fermentation approach. In contrast to conventional half-cell measurements using a liquid electrolyte, in the GDE setup CO₂ RR current densities comparable to technical cells (>100 mA cm-2) are reached without suffering from mass transport limitations of the CO₂ reactant gas. The results are of particular importance for designing CO₂ RR catalysts exhibiting high faradaic efficiencies towards CO at technological reaction rates.

Creating Chemisorption Sites for Enhanced CO2 Photoreduction Activity through Alkylamine Modification of MIL-101-Cr.

The lower CO2 utilization and poor charge conductivities have limited the application of metal-organic frameworks (MOFs) in photocatalysis. In this work, different alkylamines [ethylenediamine (EN), diethylenetriamine (DETA), and triethylenetetramine (TETA)] were successfully introduced into MIL-101-Cr by postmodification and created abundant CO2 chemisorption sites in structures. Photocatalysis reaction showed that the alkylamine modification promoted the charge separation and migration rate and enhanced the reduction potential of the electron generated by the MOF photocatalyst. Among them, the EN-modified material exhibits the highest CO generation rate of 47.2 μmol·h-1·g-1 with a high selectivity of 96.5%, much superior than the pristine MOFs MIL-101-Cr and MIL-101-SO3H, as well as the DETA- and TETA-modified products, which can be ascribed to the abundant chemisorption sites for CO2 reactants and the optimized pore size in structures. The strategy of introduction of alkylamine groups as CO2 chemisorption sites has been demonstrated to be a new pathway for the design of efficient MOF catalysts for CO2 photoreduction.

Sustainable and Self‐Enhanced Electrochemiluminescent Ternary Suprastructures Derived from CsPbBr3 Perovskite Quantum Dots

AbstractLead halide perovskite quantum dots (QDs) are promising electrochemiluminescence (ECL) nanoemitters due to their fascinating photophysical properties. However, due to their poor structural stability against the external environment, the trade‐off between their colloidal stability and carrier injection/transport efficiency is a major challenge in the advancement of perovskite‐based ECL technology. In this work, intense and stable ECL from CsPbBr3 (CPB) QDs is achieved by simultaneously encapsulating CPB QDs and coreactant (CoR) into in situ generated SiO2 matrix via hydrolysis of tetramethyl orthosilicate. The well‐designed architecture of the as‐obtained CPB‐CoR@SiO2 nanocomposites (NCs) guarantees not only greatly improved stability thanks to the peripheral SiO2 protecting matrix, but also efficient self‐enhanced ECL between CPB and the intra‐coreactants. Consequently, by elaborately selecting the CoR molecules with different tertiary/secondary amines and functional groups, multifold higher (up to 10.2 times) ECL efficiencies are obtained for the CPB‐CoR@SiO2 NCs alone in reference to the standard Ru(bpy)32+/tri‐n‐propylamine system. This work provides an efficient design strategy for obtaining stable and highly efficient ECL from perovskite QDs, and offers a new perspective for the development and application of perovskite‐based ECL system.

Improved CO2 photocatalytic reduction using a novel 3-component heterojunction

A new class of three-component photocatalyst system is designed with plasmonic AuCu nanoprisms embedded between a porous single crystalline TiO2 nanoplate thin film and polyhedral zeolitic imidazolate frameworks (ZIF-8) nanoparticles for enhanced CO2 photocatalytic reduction. The ZIF-8 plays a role of CO2 capture to enhance the reactant concentration on the catalyst, while the AuCu nanoprisms function mainly as a mediator to improve the charge density at the interfaces and facilitate the charge transfer to the CO2 adsorption sites on ZIF-8 for subsequent CO2 reduction. The reactant CO2 could be not only readily collected on the newly designed catalyst, but also more efficiently converted to CO and CH4. As a result, compared to the reference sample of two-component system of TiO2 and ZIF-8 with a CO2 conversion rate of 12.5 μmol h−1 g−1, the new three-component photocatalyst exhibited a nearly 7-fold improvement in CO2 photocatalytic reduction performance with CO2 conversion reaching an outstanding value of 86.9 μmol h−1 g−1, highlighting the importance of rational heterojunction design in facilitating reactant adsorption, charge transfer and reaction processes in photocatalysis.

Stable, High-Rate CO2 Electroreduction to Multi-Carbon Products in a Membrane Electrode Assembly System

Rising atmospheric carbon dioxide (CO2) levels have motivated the development of sustainable solutions to reduce emissions and close the carbon cycle. Several promising strategies have been proposed for the capture and utilization of CO2, including the electrochemical CO2 reduction reaction (CO2RR). Through CO2RR, CO2 can be converted to storable fuels and other valuable chemical feedstocks using intermittent renewable energy as input. Of the 16 possible CO2RR products, multi-carbon hydrocarbons and oxygenates, such as ethylene and ethanol, have received a great deal of attention as promising commercial targets due to their high energy densities and market sizes. Copper is the only transition metal capable of catalyzing the reduction of CO2 to multi-carbon products and, as such, the optimization of this electrocatalyst has been the focus of much recent work. However, to scale CO2RR technology for industrial implementation not just the catalyst, but the entire electrolyzer must be considered. Flow cell electrolyzers, which utilize gas diffusion electrodes to continuously deliver reactant CO2 to the catalyst sites, are capable of operating at the current densities necessary for industrial-scale (>100 mA/cm2). Tuning of the copper catalyst materials and structures, as well as the reaction environment through catholyte optimization, has allowed researchers to achieve high Faradaic efficiencies towards specific multi-carbon products, with low overpotentials. In addition to high reaction rates and efficiencies, both Faradaic and energetic, industrial systems will have to operate over long timescales, on the order of tens of thousands of hours. This extent of continuous operation will require stability from all components of the electrolyzer, including the gas diffusion electrode, the cathode catalyst and the anode catalyst, the electrolytes, and the ion exchange membrane. Although high Faradaic and energetic efficiencies have been achieved using alkaline electrolyzer systems, they suffer from instabilities in several system components due to the use of liquid catholyte. Catholyte-free membrane electrode assembly (MEA) systems, similar to those used in proton exchange membrane (PEM) water electrolyzers, have the potential to overcome these instability issues to produce multi-carbon products continuously over prolonged periods of operation. Here, we present our MEA electrolyzer system to convert CO2 to multi-carbon products. We compare its performance to an alkaline electrolyzer system with catholyte, to demonstrate advantages in energy efficiency, operating costs, and stability. Through the tuning of the system’s operating parameters and copper cathode catalyst, we achieve over 50% Faradaic efficiency for ethylene at current densities greater than 200 mA/cm2. Moreover, we demonstrate the stability of the catholyte-free system by operating the two-electrode configuration under potentiostatic mode at these industrially-relevant current densities continuously for over 100 hours without a decrease in ethylene Faradaic efficiency or current density.

Synergistic effects of Cu2O-decorated CeO2 on photocatalytic CO2 reduction: Surface Lewis acid/base and oxygen defect

Ceria (CeO2) with abundant oxygen defects, surface alkalinity, low cost effectiveness and admirable redox ability could be used in the photoreduction of CO2. However, little attention has been paid to the interaction of reactant CO2 molecules on CeO2–based photocatalysts. In this work, Cu2O nanoparticles were applied to the modification of the properties of Lewis acid/base, surface oxygen defect content and visible light adsorption of CeO2, and the adsorption/activation abilities of CO2 reactant on Cu2O/CeO2 and CeO2 photocatalysts were investigated in comparison. The photocatalytic performance showed that Cu2O/CeO2 had better activity than CeO2. And the loading of Cu2O resulted in more oxygen defects and Ce3+ species, which was helpful for available visible light adsorption and higher charge-separation efficiency. Furthermore, CO2-TPD, CO2-adsorption DRIFTS and in-situ ESR results demonstrated that the synergistic effects of Cu2O/CeO2 were beneficial for more generated carboxylate and CO2− radicals, instead of carbonate species which promoted CO2 reduction to CO.

Direct and Oriented Conversion of CO2 into Value-Added Aromatics.

The oriented conversion of CO2 into target high-value chemicals is an effective way to reduce carbon emissions, but still presents a challenge. In this communication, we report the oriented conversion of CO2 into value-added aromatics, especially para-xylene, in a single pass by combining core-shell structured Zn-doped H-ZSM-5 (Zn-ZSM-5@SiO2 ) and a Cr2 O3 component. Through precise regulation of the acidity of Zn-ZSM-5@SiO2 , high para-xylene selectivity (38.7 % in the total products) at a CO2 conversion of 22.1 % was achieved. Furthermore, a CO2 -assisted effect in the synthesis of aromatics during the tandem process has been clarified through a control experiment. The CO2 reactant can act as a hydrogen acceptor to accelerate the dehydrogenation of alkenes, intermediates in the synthesis of aromatics, thereby increasing the driving force towards aromatics in the tandem reaction process.

Towards Higher Rate Electrochemical CO2 Conversion: From Liquid-Phase to Gas-Phase Systems

Electrochemical CO2 conversion offers a promising route for value-added products such as formate, carbon monoxide, and hydrocarbons. As a result of the highly required overpotential for CO2 reduction, researchers have extensively studied the development of catalyst materials in a typical H-type cell, utilizing a dissolved CO2 reactant in the liquid phase. However, the low CO2 solubility in an aqueous solution has critically limited productivity, thereby hindering its practical application. In efforts to realize commercially available CO2 conversion, gas-phase reactor systems have recently attracted considerable attention. Although the achieved performance to date reflects a high feasibility, further development is still required in order for a well-established technology. Accordingly, this review aims to promote the further study of gas-phase systems for CO2 reduction, by generally examining some previous approaches from liquid-phase to gas-phase systems. Finally, we outline major challenges, with significant lessons for practical CO2 conversion systems.

In Situ Electronic Probing of Photoconductive Trap States for the Catalytic Reduction of CO2 by In2O3- xOH y Nanorods.

We use photoconductivity time, optical absorption, and electron quantum efficiency measurements under in situ reactant CO2 + H2 atmospheres to determine the role of surface trap states during photoreduction of CO2 to CO using In2O3- xOH y nanorods of varied annealing times. Photocurrent decay trends show an asymmetric energy distribution of surface barrier potentials with increased asymmetry from vacuum to CO2 + H2. Urbach analysis shows crystalline disorder parameters of 0.35-0.40 under vacuum and 0.45-0.6 under CO2 + H2. Quantum efficiency spectra show that under H2 + CO2 average tail state energies are similar to those under vacuum but with increased densities of photoconductive gap states. Photoelectro-paramagnetic-resonance measurements show the creation of new paramagnetic centers. Overall, enhanced activity is associated with a lower maximum barrier potential of 0.39 eV than that of 0.41 eV, lower average trap energies of 2.58 eV compared to 2.69 eV, with higher disorder due to increased surface state densities. These techniques pave the way for facile in situ probing of gas-phase photocatalysts, providing simple macrolevel understanding of adsorbed reactants on surface band bending, thus correlating to catalytic efficacy.

Gas-Diffusion Electrodes for Carbon Dioxide Reduction: A New Paradigm

Significant advances have been made in recent years discovering new electrocatalysts and developing a fundamental understanding of electrochemical CO2 reduction processes. This field has progressed to the point that efforts can now focus on translating this knowledge toward the development of practical CO2 electrolyzers, which have the potential to replace conventional petrochemical processes as a sustainable route to produce fuels and chemicals. In this Perspective, we take a critical look at the progress in incorporating electrochemical CO2 reduction catalysts into practical device architectures that operate using vapor-phase CO2 reactants, thereby overcoming intrinsic limitations of aqueous-based systems. Performance comparison is made between state-of-the-art CO2 electrolyzers and commercial H2O electrolyzers—a well-established technology that provides realistic performance targets. Beyond just higher rates, vapor-fed reactors represent new paradigms for unprecedented control of local reaction conditi...

Versatile Synthesis of Pd and Cu Co-Doped Porous Carbon Nitride Nanowires for Catalytic CO Oxidation Reaction

Developing efficient catalyst for CO oxidation at low-temperature is crucial in various industrial and environmental remediation applications. Herein, we present a versatile approach for controlled synthesis of carbon nitride nanowires (CN NWs) doped with palladium and copper (Pd/Cu/CN NWs) for CO oxidation reactions. This is based on the polymerization of melamine by nitric acid in the presence of metal-precursors followed by annealing under nitrogen. This intriguingly drove the formation of well-defined, one-dimensional nanowires architecture with a high surface area (120 m2 g−1) and doped atomically with Pd and Cu. The newly-designed Pd/Cu/CN NWs fully converted CO to CO2 at 149 °C, that was substantially more active than that of Pd/CN NWs (283 °C) and Cu/CN NWs (329 °C). Moreover, Pd/Cu/CN NWs fully reserved their initial CO oxidation activity after 20 h. This is mainly attributed to the combination between the unique catalytic properties of Pd/Cu and outstanding physicochemical properties of CN NWs, which tune the adsorption energies of CO reactant and reaction product during the CO oxidation reaction. The as-developed method may open new frontiers on using CN NWs supported various noble metals for CO oxidation reaction.

Influence of the swelling agents of siliceous mesocellular foams on the performances of Ni-based methane dry reforming catalysts

For the first time, n-octane was tested as a swelling agent for the synthesis of a mesocellular silica foam (MCF(O)) and the latter was used as a Ni support for the dry reforming of methane reaction (DRM). Using n-Octane led to a MCF(O) material with smaller cells size (14 nm) than in conventional MCF(T) prepared in the presence of 1,3,5 trimethylbenzene (21 nm). Nickel precursor addition was done either by post-synthesis impregnation on preformed silica (incipient wetness impregnation (IWI), “two-solvents” (TS)) or during the synthesis of MCF (Direct synthesis, DS). All prepared materials were characterized in their calcined and reduced forms using N2 sorption, X-Ray Diffraction (XRD), Transmission Electronic Microscopy (TEM), Temperature Programmed Reduction (TPR) and X-Ray Fluorescence (XRF). A highly dispersed Ni0 active phase, mainly located in the MCF walls, as well as strong Ni-support interaction were emphasized for Ni-MCF(O)-DS. The catalytic performances of all the samples were investigated in DRM between 200 and 770 °C, then for 4 h (stability test) at 650 °C, using a Gas Hourly Space Velocity (GHSV) of 36 L g−1 h−1 and an equimolar ratio of CH4 and CO2 reactants. The Ni-MCF(O)-TS catalyst prepared by means of the “two-solvents” impregnation exhibited the highest CH4 and CO2 conversions. Compared to Ni-MCF(T), better performances were obtained with Ni-MCF(O) solids.

High rate CO2 photoreduction using flame annealed TiO2 nanotubes

The photocatalytic reduction of CO2 into light hydrocarbons using sunlight and water is a challenging reaction involving eight electron transfer steps; nevertheless, it has great potential to address the problem of rising anthropogenic carbon emissions and enable the use of fossil fuels in a sustainable way. Several decades after its first use, TiO2 remains one of the best performing and most durable photocatalysts for CO2 reduction albeit with a poor visible light absorption capacity. We have used flame annealing to improve the response of TiO2 to visible photons and engineered a nanotubular morphology with square-shaped cross-sections in flame-annealed nanotubes. An enhanced CH4 yield was achieved in the photoreduction of CO2 using flame annealed TiO2 nanotubes, and isotope labeled experiments confirmed the reaction products to originate from the CO2 reactant. Flame-annealed TiO2 nanotubes formed in aqueous electrolyte (FANT-aq) yielded 156.5 μmol gcatalyst–1.hr–1 of CH4, which is in the top tier of reported performance values achieved using TiO2 as a stand-alone photocatalyst. This performance resulted because appreciable amounts of CH4 were generated under visible light illumination as well. TiO2 nanotubes exhibited CO2 photoreduction activity up to a wavelength of 620 nm with visible light driven photocatalytic activity peaking at 450 nm for flame annealed TiO2 nanotubes. Isotope labelling studies, using GC–MS and gas-phase FTIR, indicated photoreduction of 13CO2 to 13CH4. The detection of 13CO in the product mixture, and the absence of HCHO and HCOOH provides strong support for the photoreduction proceeding along a carbene pathway. The enhanced CO2 photoreduction performance of FANT-aq is attributed to increased visible light absorption, square morphology, and the presence of rutile as the only crystalline phase with (110) as the dominant plane.

Characterization of CoCu- and CoMn-Based Catalysts for the Fischer–Tropsch Reaction Toward Chain-Lengthened Oxygenates

The need for a sustainable energy supply in the face of depleting oil reserves has reignited the importance of Fischer–Tropsch (FT) synthesis technology. Presently, the FT process is practiced at the industrial scale to predominately produce synthetic diesel-type fuels and lubricants. More recently, the possibility of hydrogenating CO toward oxygenates, and not just hydrocarbons, has been explored. We have developed a series of CoCuMn and CoMnK catalysts prepared via the oxalate co-precipitation route that are capable of forming oxygenates with desirable selectivity. Upon H2-assisted thermal decomposition of the resultant mixed metal Co1Cu1Mn1 oxalates, catalysts naturally exhibited a cobalt core–copper shell configuration with Mn5O8 dispersed throughout the catalyst nanoparticle as determined via Atom Probe Tomography (APT). We suggest structural changes are induced by the CO and H2 reactants to form the catalytically active phase under real-time reaction conditions as demonstrated by corroborative Density Functional Theory calculations and experimental evidence. APT studies also show that a Co4Mn1K0.1 catalyst post reaction contained a cobalt carbide phase as determined from a Co/C ratio of 2/1. Manganese and potassium were found only in the outermost part of the particle. Both catalysts were found to contain the presence of a Mn5O8 oxidic phase before and post reaction which we attribute to the high activity toward oxygenates of these two catalysts.

Heterogeneously catalyzed two-step cascade electrochemical reduction of CO2 to ethanol

Electrochemical reduction of CO2 to liquid fuels is a promising route to a carbon-neutral, energy-dense storage of intermittent renewable electricity. However, electrocatalysts generally suffer from high overpotential and poor selectivity for multi-carbon products such as ethanol, and efforts to enhance such catalysts are limited by scaling relations which inhibit a simultaneous optimization of each elementary electrochemical step. In this work, the multistep proton-coupled electron-transfer reaction for the conversion of CO2 to C2H5OH was strategically divided into two independently optimized steps in a sequential cascade reaction using heterogeneous electrocatalysts to convert CO2 to CO and CO to C2H5OH within a single integrated electrochemical system. The exclusion of CO2 reactant from the second-stage electrolyzer was observed to be critical for maintaining appreciable ethanol selectivity. The cascade system produced C2H5OH at an overall faradaic efficiency of 11.0% at an average applied potential of −0.52 V vs. RHE, making it highly competitive with known single-step electrocatalysts for ethanol production from CO2. This performance was despite limited conversion of the intermediate CO between cascade steps (∼6.4%), and reactor design improvements to enhance the conversion could lead to significantly enhanced ethanol production performance.

Green and sustainable methanol production from CO2 over magnetized Fe[sbnd]Cu/core–shell and infiltrate mesoporous silica-aluminosilicates

In this present work, green and efficient utilization concepts in the form of the use of an external magnetic field have been applied to improve catalytic performance in CO2 hydrogenation. The 10Fe10Cu catalysts with two types of supports, core–shell and infiltrate mesoporous silica-aluminosilicate materials, were applied under external magnetic fields of different intensities (0, 20.8 mT, 27.7 mT) and orientations (north-to-south (N–S), south-to-north (S–N) directions). It was found that a magnetic field considerably enhanced both CO2 conversion and methanol and DME selectivities. The highest CO2 conversion was obtained over 10Fe10Cu/infiltrate catalyst under the magnetic field conditions of 27.7 mT and 4N–S direction at 260 °C (conversion was 1.5 times greater than that without a magnetic field). Under such conditions and at 240 °C, the highest methanol and DME space time yields were obtained, with results 1.8–1.9 times higher than those of without a magnetic field. These excellent performances could be ascribed to the superior adsorption of CO2 and H2 reactant gas molecules over the surface of magnetized catalysts under external magnetic field. This leads to the advantages of the catalyzed CO2 hydrogenation–decreases in the operating temperature and simultaneous reduction in CO2 emission to the atmosphere. This therefore facilitates a carbon-neutral route of CO2 utilization.

Graphene-wrapped Pt/TiO2 photocatalysts with enhanced photogenerated charges separation and reactant adsorption for high selective photoreduction of CO2 to CH4

Artificial photosynthesis efficiency for selective CO2 conversion to CH4 as chemical energy-rich molecule is dependent on the photogenerated charges separation and reactant adsorption property of photocatalyst. Here we report a novel fabrication of core-shell-structured photocatalysts of Pt/TiO2-nanocrystals wrapped by reduced graphene oxide (rGO) sheets ((Pt/TiO2)@rGO). The ultrafine anatase TiO2 nanocrystals with coexposed {001} and {101} facets acted as the fountain of the photogenerated charges primitively. Pt nanoparticles (NPs) deposited on the TiO2 nanocrystals can gather and transfer the stimulated electrons originated from anatase TiO2 nanocrystals. The all-solid-state electron multiple transmission (EMT) system with TiO2-nanocrystal(core)-Pt(mediator)-rGO(shell) nanojunction is not only favorable to the vectorial electron transfer of TiO2 → Pt → rGO and enhance the separation efficiency of photogenerated electrons and holes, but also the surface residual hydroxyl and extended π bond of wrapping rGO sheets can improve the adsorption and activation capabilities for CO2 reactant. (Pt/TiO2)@rGO ternary photocatalysts exhibit excellent performance for the multi-electron process of selective photocatalytic CO2 conversion to CH4. Among the prepared catalysts, (Pt/TiO2)@rGO-2 catalyst shows the highest photocatalytic activity and selectivity for CO2 conversion, i.e., the formation rate of CH4 is 41.3 μmol g−1 h−1 and the selectivity of CO2 conversion to CH4 product is 99.1%, and its apparent quantum efficiency for CH4 product is 1.93%. As a heuristic the fabrication of core-shell structured (Pt/TiO2)@rGO photocatalysts will stimulate more novel ideas for application to light-chemical energy conversion.