Photocatalytic O_(2)activation to generate reactive oxygen species is crucially important for purifying organic pollutants,yet remains a challenge due to poor adsorption of O_(2)and low efficiency of electron transfer...Photocatalytic O_(2)activation to generate reactive oxygen species is crucially important for purifying organic pollutants,yet remains a challenge due to poor adsorption of O_(2)and low efficiency of electron transfer.Herein,we demonstrate that ultrafine MoO_(x)clusters anchored on graphitic carbon nitride(g-C_(3)N_(4))with dual nitrogen/oxygen defects promote the photocatalytic activation of O_(2)to generate·O_(2)−for the degradation of tetracycline hydrochloride(TCH).A range of characterization techniques and density functional theory(DFT)calculations reveal that the introduction of the nitrogen/oxygen dual defects and MoO_(x)clusters enhances the O_(2)adsorption energy from−2.77 to−2.94 eV.We find that MoO_(x)clusters with oxygen vacancies(Ov)and surface Ov-mediated Moδ+(3≥δ≥2)possess unpaired localized electrons,which act as electron capture centers to transfer electrons to the MoO_(x)clusters.These electrons can then transfer to the surface adsorbed O_(2),thus promoting the photocatalytic conversion of O_(2)to·O_(2)−and,simultaneously,realizing the efficient separation of photogenerated electron–hole pairs.Our fully-optimized MoO_(x)/g-C_(3)N_(4)catalyst with dual nitrogen/oxygen defects manifests outstanding photoactivities,achieving 79%degradation efficiency toward TCH within 120 min under visible light irradiation,representing nearly 7 times higher activity than pristine g-C_(3)N_(4).Finally,based on the results of liquid chromatograph mass spectrometry and DFT calculations,the possible photocatalytic degradation pathways of TCH were proposed.展开更多
Electrochemical CO_(2) transformation to high‐value ethylene(C_(2)H_(4))at high currents and efficiencies is desired and yet remains a grand challenge.We show for the first time that coupling single Sb atoms and oxyg...Electrochemical CO_(2) transformation to high‐value ethylene(C_(2)H_(4))at high currents and efficiencies is desired and yet remains a grand challenge.We show for the first time that coupling single Sb atoms and oxygen vacancies of CuO enable synergistic electrocatalytic reduction of CO_(2) to C_(2)H_(4) at low overpotentials.Highly dispersed Sb atoms occupying metal substitutional sites of CuO are synthesized under mild conditions.The overall CO_(2) reduction faradaic efficiency(FE)reaches 89.3±1.1%with an FE toward C_(2)H_(4) exceeding 58.4%at a high‐current density of 500 mA/cm^(2).Addition of the p‐block metal is found to induce transformation of CuO from flakes to nanoribbons rich in nanoholes and oxygen vacancies,greatly enhancing CO_(2) adsorption and activation while suppressing hydrogen evolution.Further density functional theory calculations with in situ X‐ray diffraction reveal that combining Sb sites and oxygen vacancies prominently lessen the dimerization energy of adsorbed CO intermediate,thus boosting the conversion of CO_(2) to produce C_(2)H_(4).This study provides a new perspective for promoting selective C-C coupling for electrochemical CO_(2) reduction.展开更多
Demand for ammonia continues to increase to sustain the growing global population.The direct electrochemical N2 reduction reaction(NRR)powered by renewable electricity offers a promising carbon-neutral and sustainable...Demand for ammonia continues to increase to sustain the growing global population.The direct electrochemical N2 reduction reaction(NRR)powered by renewable electricity offers a promising carbon-neutral and sustainable strategy for manufacturing NH3,yet achieving this remains a grand challenge.Here,we report a synergistic strategy to promote ambient NRR for ammonia production by tuning the Te vacancies(VTe)and surface hydrophobicity of two-dimensional TaTe_(2)nanosheets.Remarkable NH3 faradic efficiency of up to 32.2%is attained at a mild overpotential,which is largely maintained even after 100 h of consecutive electrolysis.Isotopic labeling validates that the N atoms of formed NH4+originate from N2.In situ X-ray diffraction indicates preservation of the crystalline structure of TaTe_(2)during NRR.Further density functional theory calculations reveal that the potential-determining step(PDS)is*NH_(2)+(H^(+)+e^(-))/NH3 on VTe-TaTe_(2)compared with that of*+N2+(H^(+)+e^(-))/*N-NH on TaTe_(2).We identify that the edge plane of TaTe_(2)and VTe serve as the main active sites for NRR.The free energy change at PDS on VTe-TaTe_(2)is comparable with the values at the top of the NRR volcano plots on various transition metal surfaces.展开更多
基金supported by the National Natural Science Foundation of China(No.21972010)the National Key Research and Development Program of China(No.2022YFC2105900).
文摘Photocatalytic O_(2)activation to generate reactive oxygen species is crucially important for purifying organic pollutants,yet remains a challenge due to poor adsorption of O_(2)and low efficiency of electron transfer.Herein,we demonstrate that ultrafine MoO_(x)clusters anchored on graphitic carbon nitride(g-C_(3)N_(4))with dual nitrogen/oxygen defects promote the photocatalytic activation of O_(2)to generate·O_(2)−for the degradation of tetracycline hydrochloride(TCH).A range of characterization techniques and density functional theory(DFT)calculations reveal that the introduction of the nitrogen/oxygen dual defects and MoO_(x)clusters enhances the O_(2)adsorption energy from−2.77 to−2.94 eV.We find that MoO_(x)clusters with oxygen vacancies(Ov)and surface Ov-mediated Moδ+(3≥δ≥2)possess unpaired localized electrons,which act as electron capture centers to transfer electrons to the MoO_(x)clusters.These electrons can then transfer to the surface adsorbed O_(2),thus promoting the photocatalytic conversion of O_(2)to·O_(2)−and,simultaneously,realizing the efficient separation of photogenerated electron–hole pairs.Our fully-optimized MoO_(x)/g-C_(3)N_(4)catalyst with dual nitrogen/oxygen defects manifests outstanding photoactivities,achieving 79%degradation efficiency toward TCH within 120 min under visible light irradiation,representing nearly 7 times higher activity than pristine g-C_(3)N_(4).Finally,based on the results of liquid chromatograph mass spectrometry and DFT calculations,the possible photocatalytic degradation pathways of TCH were proposed.
基金National Natural Science Foundation of China,Grant/Award Number:21972010Beijing Natural Science Foundation,Grant/Award Number:2192039NRF Korea,Grant/Award Number:NRF-2016M3D1A1021147。
文摘Electrochemical CO_(2) transformation to high‐value ethylene(C_(2)H_(4))at high currents and efficiencies is desired and yet remains a grand challenge.We show for the first time that coupling single Sb atoms and oxygen vacancies of CuO enable synergistic electrocatalytic reduction of CO_(2) to C_(2)H_(4) at low overpotentials.Highly dispersed Sb atoms occupying metal substitutional sites of CuO are synthesized under mild conditions.The overall CO_(2) reduction faradaic efficiency(FE)reaches 89.3±1.1%with an FE toward C_(2)H_(4) exceeding 58.4%at a high‐current density of 500 mA/cm^(2).Addition of the p‐block metal is found to induce transformation of CuO from flakes to nanoribbons rich in nanoholes and oxygen vacancies,greatly enhancing CO_(2) adsorption and activation while suppressing hydrogen evolution.Further density functional theory calculations with in situ X‐ray diffraction reveal that combining Sb sites and oxygen vacancies prominently lessen the dimerization energy of adsorbed CO intermediate,thus boosting the conversion of CO_(2) to produce C_(2)H_(4).This study provides a new perspective for promoting selective C-C coupling for electrochemical CO_(2) reduction.
基金supported by the National Natural Science Foundation of China(no.21972010)Beijing Natural Science Foundation(no.2192039)+3 种基金the State Key Laboratory of Organic-Inorganic Composites(no.oic201901001)Beijing University of Chemical Technology(XK180301)NRF Korea(NRF-2016M3D1A1021147)the facilities of the DCCEM,at the Materials Department,Oxford(EP/R010145/1).
文摘Demand for ammonia continues to increase to sustain the growing global population.The direct electrochemical N2 reduction reaction(NRR)powered by renewable electricity offers a promising carbon-neutral and sustainable strategy for manufacturing NH3,yet achieving this remains a grand challenge.Here,we report a synergistic strategy to promote ambient NRR for ammonia production by tuning the Te vacancies(VTe)and surface hydrophobicity of two-dimensional TaTe_(2)nanosheets.Remarkable NH3 faradic efficiency of up to 32.2%is attained at a mild overpotential,which is largely maintained even after 100 h of consecutive electrolysis.Isotopic labeling validates that the N atoms of formed NH4+originate from N2.In situ X-ray diffraction indicates preservation of the crystalline structure of TaTe_(2)during NRR.Further density functional theory calculations reveal that the potential-determining step(PDS)is*NH_(2)+(H^(+)+e^(-))/NH3 on VTe-TaTe_(2)compared with that of*+N2+(H^(+)+e^(-))/*N-NH on TaTe_(2).We identify that the edge plane of TaTe_(2)and VTe serve as the main active sites for NRR.The free energy change at PDS on VTe-TaTe_(2)is comparable with the values at the top of the NRR volcano plots on various transition metal surfaces.
