Search query: Ag CO2 reduction

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abstract: Abstract To construct semiconductor based photocatalysts for carbon dioxide (CO2) reduction with high activity and stability remains a long term goal. Herein, we report a ternary Ag Cu2O/ZnO nanorods (NRs) hybrid catalyst with efficient charge carrier separation/transfer and CO2 adsorption capacity, which demonstrates much improved activity in comparison with bare ZnO NRs for photocatalytic CO2 reduction to carbon monoxide (CO) under UV vis light. Mechanistic studies reveal that the deposited Cu2O enhances the CO2 chemisorption on the surface of catalysts and the formation of Z scheme system between Cu2O and ZnO facilitates the photogenerated charge separation. The subsequent assembly of Ag nanoparticles (NPs) onto Cu2O is able to further promote the transfer of electrons due to the "electron sink" effect of Ag, which leads to the higher photocatalytic activity. As such, the synergy effect of strong CO2 chemisorption and multiple electrons transfer results in the boosted photocatalytic activity of Ag Cu2O/ZnO NRs for CO2 reduction. In addition, compared with the binary Cu2O/ZnO NRs, the activity of Ag Cu2O/ZnO NRs can be well maintained after multiple cycle reaction. The possible reason is that the deposited Ag can alleviate the self photoreduction of Cu2O by transferring the excess electrons accumulated in the conduction band (CB) of Cu2O, thus preserving the stability of the Ag Cu2O/ZnO NRs photocatalyst.
author_names: Fengyu Zhang

Yonggui Li

Ming-Yu Qi

Zi-Rong Tang

Yi-Jun Xu
title: Boosting the activity and stability of Ag Cu2O/ZnO nanorods for photocatalytic CO2 reduction
year: 2020

abstract: Abstract Spinel ZnFe2O4 microspheres coupled with Ag/TiO2 nanorods (NRs) to develop Z scheme heterojunction were fabricated using a facile hydrothermal approach and were tested for photocatalytic CO2 conversion to fuels. ZnFe2O4/Ag/TiO2 NRs composite presents remarkably improved CO2 photo activity for CO production, which was 1.49 folds higher than ZnFe2O4/TiO2 NRs and 4.12 times that using pristine ZnFe2O4 microspheres. Similar trends were obtained to produce methane and methanol over composite catalyst. Selective CO and hydrocarbon fuels production was obviously due to double charge transfer approach in indirect Z scheme heterojunction with superior charge carrier separation and high visible light absorption. Interestingly, CO evolution under visible light with ZnFe2O4/Ag/TiO2 NRs was declined by 7.48 folds than using UV light irradiation. This was apparently due to the inappropriate VB position of ZnFe2O4 for stimulating CO2 reduction under visible light irradiation. Comparing morphological effects, coupling TiO2 NRs with Ag/ZnFe2O4, production of CO was 1.40 folds higher than using TiO2 NPs with Ag/ZnFe2O4 composite due to 1D TiO2 NRs and ZnF2O4 were beneficial for promoting charge carrier separation. This work provides a new approach for preparing ZnFe2O4 based structured Z scheme hetero junction for stimulating photocatalytic conversion of CO2 to selective fuels and would be promising for energy application.
author_names: Muhammad Tahir
title: Well designed ZnFe2O4/Ag/TiO2 nanorods heterojunction with Ag as electron mediator for photocatalytic CO2 reduction to fuels under UV/visible light
year: 2020

abstract: Abstract Graphitic carbon nitride (g C3N4) usually exhibits weak photocatalytic activity for CO2 reduction and pollutant degradation. Herein, the visible light activities of g C3N4 nanosheets are successfully improved by co modifying SnO2 and Ag, with ~10 time and ~8 time improvement respectively for CO2 conversion and 2,4 dichlorophenol (2,4 DCP) degradation as compared to the pure g C3N4. Mainly based on the transient state surface photovoltage responses, transient state photoluminescence spectra and electrochemical analyses, it is confirmed that the improved photoactivities are attributed to the synergistic effect of the prolonged charge lifetime and the provided catalytic function by modifying SnO2 and Ag, respectively. In addition, the synergistic effect is also feasible by replacing Ag with Au. This work will provide an effective strategy for designing high activity g C3N4 based photocatalysts.
author_names: Wajid Ali

Xuliang Zhang

Xinxin Zhang

Sharafat Ali

Lina Zhao

Shabana Shaheen

Liqiang Jing
title: Improved visible light activities of g C3N4 nanosheets by co modifying nano sized SnO2 and Ag for CO2 reduction and 2,4 dichlorophenol degradation
year: 2020

abstract: Understanding the structural and compositional sensitivities of the electrochemical CO2 reduction reaction (CO2RR) is fundamentally important for developing highly efficient and selective electrocatalysts. Here, we use Ag/Cu nanocrystals to uncover the key role played by the Ag/Cu interface in promoting CO2RR. Nanodimers including the two constituent metals as segregated domains sharing a tunable interface are obtained by developing a seeded growth synthesis, wherein preformed Ag nanoparticles are used as nucleation seeds for the Cu domain. We find that the type of metal precursor and the strength of the reducing agent play a key role in achieving the desired chemical and structural control. We show that tandem catalysis and electronic effects, both enabled by the addition of Ag to Cu in the form of segregated nanodomain within the same catalyst, synergistically account for an enhancement in the Faradaic efficiency for C2H4 by 3.4 fold and in the partial current density for CO2 reduction by 2 fold compared with the pure Cu counterpart. The insights gained from this work may be beneficial for designing efficient multicomponent catalysts for electrochemical CO2 reduction.
author_names: Jianfeng Huang

M Driss Mensi

Emad Oveisi

Valeria Mantella

Raffaella Buonsanti
title: Structural Sensitivities in Bimetallic Catalysts for Electrochemical CO2 Reduction Revealed by Ag Cu Nanodimers.
venue: Journal of the American Chemical Society
year: 2019

abstract: Abstract The electrocatalytic reduction of carbon dioxide (CO2) is a promising way to reduce CO2 and to produce valuable products. However, CO2 reduction still have challenges, such as, low catalytic activity, selectivity, and stability of catalysts. In the present study, we prepared Ag nanolayers (2, 5, and 10 nm) sputtered on polycrystalline Zn (AgZn) catalysts by a physical vapor deposition for the electrochemical CO2 reduction to carbon monoxide (CO) Among them, a 2 nm Ag layer deposited catalyst on Zn showed the faradaic efficiency of 84.2% with a CO partial current density of 2.97 mA cm 2 at 1.0 V vs. RHE. Such enhanced electrochemical reduction activity, selectivity, and stability were attributed to the synergetic effect between Ag and Zn, which was confirmed by X ray photoelectron spectroscopy (XPS) data. The results indicate that the proposed catalyst can provide one of efficient ways for the CO2 reduction reaction.
author_names: Wen Guo

Kyu-Seung Shim

Yong-Tae Kim
title: Ag layer deposited on Zn by physical vapor deposition with enhanced CO selectivity for electrochemical CO2 reduction
year: 2020

abstract: Silver nanostructures with hierarchical porosities of multiple length scales have been synthesized through electrochemical reduction of silver benzenethiolate nanoboxes. The porous Ag nanostructures exhibit superior catalytic performance towards electrochemical reduction of CO2. The Faradaic efficiency of reducing CO2 to CO can be close to 100% at high cathodic potentials, benefiting from the re adsorbed benzenethiolate ions on Ag surface that can suppress hydrogen evolution reaction (HER) Density functional theory calculations using SCAN functional reveal that the disfavored H binding on the benzenethiolate modified Ag surface is responsible for inhibiting HER. The mass specific activity of CO2 reduction can be over 500 A/g because the multiple scale porosities maximize the diffusion of reactive species to and away from the Ag surface. The unique multiscale porosities and surface modification of the as synthesized Ag nanostructures make them a class of promising catalysts for electrochemical reduction of CO2 in protic electrolytes to achieve maximum activity and selectivity.
author_names: Sasitha C Abeyweera

Jie Yu

John P Perdew

Qimin Yan

Yugang Sun
title: Hierarchically 3D Porous Ag Nanostructures Derived from Silver Benzenethiolate Nanoboxes: Enabling CO2 Reduction with a Near Unity Selectivity and Mass Specific Current Density over 500 A/g.
venue: Nano letters
year: 2020

abstract: Abstract The electrochemical conversion of waste carbon dioxide into hydrocarbon fuels represent a promising strategy for clean and sustainable energy production. However, the design of outstanding electrocatalysts that can reduce CO2 in an efficient and selective manner is challenging, and the fundamental understanding on reaction mechanism is still limited. Herein, we report the preparation of self supported Ag Cu bimetallic catalysts with bicontinuous nanoporous geometries and adjustable compositions through an electrochemical anodizing/dealloying process of Ag52Cu39Sn9 alloy foil to exploit their performances in electrocatalytic CO2 reduction. By changing the compositions from Ag91Cu9 to Ag65Cu35, the variations in atomic arrangement and electronic structure around the active sites bring synergistic effects on the binding strength of different reaction intermediates, realizing tunable product selectivity from CO to formate at high Faradaic efficiencies. In situ Raman analysis and density functional theory calculations confirm that as the Ag Cu atomic ratio shifts, the variations of formation free energies and desorption capacities of intermediates lead to different reaction pathways and final products. The findings in this study provide a promising route to modulate the atomic structures and improve the properties of electrocatalysts towards CO2 fixation.
author_names: Wenjun Zhang

Chenhong Xu

Y Hu

Songyuan Yang

Lianbo Ma

L Wang

Peiyang Zhao

Caixing Wang

Jing Ma

Zhong Jin
title: Electronic and geometric structure engineering of bicontinuous porous Ag Cu nanoarchitectures for realizing selectivity tunable electrochemical CO2 reduction
year: 2020

abstract: Abstract It is significant to enhance the charge separation and extend the visible light range for the TS 1 molecular sieve based photocatalysts to improve the photocatalytic performance for CO2 reduction reaction (CO2RR) Here, dimension matched 2D/2D hydroxylated g C3N4/TS 1 (hCN/TS 1) nanocomposites have been successfully fabricated and further modified by nanosized Ag by the photoreduction method. The optimum Ag modified hCN/TS 1 exhibits 7 time CO2 conversion than that of 2D TS 1. Based on the surface photovoltage responses, monochromatic photocurrent action spectra and electrochemical reduction curves, it is confirmed that the exceptional photoactivity is attributed to the greatly enhanced charge separation via the Z scheme mode between hCN and TS 1 at intimately connected interfaces, extended visible light absorption endowed by hCN, and Ag nanoparticles as the effective electron capturers with favorable catalytic function for activating CO2 molecules. This work showcases an effective and feasible design strategy to fabricate highly effective TS 1 molecular sieve based photocatalysts for practical application.
author_names: Wensen Li
title: Synthesis of nanosized Ag modified 2D/2D hydroxylated g C3N4/TS 1 Z scheme nanocomposites for efficient photocatalytic CO2 reduction
year: 2020

abstract: Abstract Artificial photosynthesis from CO2 reduction to methane is severely hampered by the kinetically challenging eight electron transfer process. Accumulated electrons has been demonstrated can decrease this kinetic barrier. However, charge accumulation were mainly reported in several homogenous systems because of its difficulties in heterogenous systems. Here we identify that highly accumulated electrons exist in Au loaded ultrathin MoS2 under light irradiation, resulting in a superior performance of CO2 reduction to methane. The selectivity for methane is up to 80 with an average production rate of about 19.38 mmolg 1 h 1 in pure water. Further detailed studies reveal that plasmon excited hot electrons transfer from Au to charged excitons in ultrathin MoS2 promotes electron accumulation and multi electron CO2 reduction kinetics for methane generation. This is further supported by the CO2 reduction performance of Ag MoS2. Along with the vanished accumulated electrons, CO is the main product with a selectivity of 98
author_names: Songmei Sun

Qi An

Motonori Watanabe

Ju-Hsiang Cheng

Hack Ho Kim

Taner Akbay

Atsushi Takagaki

Tatsumi Ishihara
title: Highly correlation of CO2 reduction selectivity and surface electron Accumulation: A case study of Au MoS2 and Ag MoS2 catalyst
year: 2020

abstract: The design and preparation of novel photocatalysts to enhance photocatalytic activity and selectivity for CO2 reduction is highly important both theoretically and practically. Herein, we develop an electrospinning and wet impregnation method to obtain an Ag and MgO co modified TiO2 nanofibrous mat. Ag nanoparticles (NPs) as electron traps can effectively separate electron hole pairs and reduce their recombination in TiO2 nanofibres due to the formation of Schottky barriers. Accumulation of photogenerated electrons in the Ag NPs can enhance the formation of CH4. The obtained Ag MgO TiO2 composite mat exhibits extended visible light absorption owing to the surface plasmon resonance effect of the Ag NPs. Deposition of MgO NPs, as basic sites, could facilitate the adsorption of CO2 molecules. The synergetic effects of Ag and MgO as a bi cocatalyst contribute to enhanced photocatalytic activity and CH4 selectivity for CO2 reduction. Isotope (13C) tracer experiments confirm that the products are produced from photocatalytic reduction of the CO2 source instead of organic contaminants. This report highlights the importance of the synergistic effect of Ag and MgO NPs on enhancing the photocatalytic activity and selectivity of TiO2 based materials.
author_names: Feiyan Xu

Kai Meng

Bei Cheng

Jiaguo Yu

Wingkei Ho
title: Enhanced Photocatalytic Activity and Selectivity for CO2 Reduction over a TiO2 Nanofibre Mat Using Ag and MgO as Bi Cocatalyst
year: 2019