NiS2 is a promising cocatalyst to improve the photocatalytic performance of g-C3N4 for the production of H2.However,the synthesis of the NiS2 cocatalyst usually requires harsh conditions,which risks destroying the mic...NiS2 is a promising cocatalyst to improve the photocatalytic performance of g-C3N4 for the production of H2.However,the synthesis of the NiS2 cocatalyst usually requires harsh conditions,which risks destroying the microstructures of the g-C3N4 photocatalysts.In this study,a facile and low-temperature（80 ℃） impregnation method was developed to prepare NiS2/g-C3N4 photocatalysts.First,the g-C3N4 powders were processed by the hydrothermal method in order to introduce oxygen-containing functional groups（such as-OH and-C0NH-） to the surface of g-C3N4.Then,the Ni^2＋ ions could be adsorbed near the g-C3N4 via strong electrostatic interaction between g-C3N4 and Ni^2＋ ions upon the addition of Ni（NO3）2 solution.Finally,NiS2 nanoparticles were formed on the surface of g-C3N4 upon the addition of TAA.It was found that the NiS2 nanoparticles were solidly and homogeneously grafted on the surface of g-C3N4,resulting in greatly improved photocatalytic H2production.When the amount of NiS2 was 3 wt%,the resultant NiS2/g-C3N4 photocatalyst showed the highest H2 evolution rate（116.343 μmol h^-1 g^-1）,which is significantly higher than that of the pure g-C3N4（3 μmol h^-1 g^-1）.Moreover,the results of a recycling test for the NiS2/g-C3N4（3 wt%）sample showed that this sample could maintain a stable and effective photocatalytic H2-evolution performance under visible-light irradiation.Based on the above results,a possible mechanism of the improved photocatalytic performance was proposed for the presented NiS2/g-C3N4 photocatalysts,in which the photogenerated electrons of g-C3N4 can be rapidly transferred to the NiS2 nanoparticles via the close and continuous contact between them;then,the photogenerated electrons rapidly react with H2O adsorbed on the surface of NiS2,which has a surficial metallic character and high catalytic activity,to produce H2.Considering the mild and facile synthesis method,the presented low-cost and highly efficient NiS2-modified g-C3N4 photocatalysts would have great potential for practical use in photocatalytic H2 production.展开更多
The development of highly active and stable reversible oxygen electrocatalysts is crucial for improving the efficiency of metal‐air battery devices.Herein,an efficient liquid exfoliation strategy was designed for pro...The development of highly active and stable reversible oxygen electrocatalysts is crucial for improving the efficiency of metal‐air battery devices.Herein,an efficient liquid exfoliation strategy was designed for producing silk‐like FeS2/NiS2 hybrid nanocrystals with enhanced reversible oxygen catalytic performance that displayed excellent properties for Zn‐air batteries.Because of the unique silk‐like morphology and interface nanocrystal structure,they can catalyze the oxygen evolution reaction(OER)efficiently with a low overpotential of 233 mV at j=10 mA cm?2.This is an improvement from the recently reported catalysts in 1.0 M KOH.Meanwhile,the oxygen reduction reaction(ORR)activity of the silk‐like FeS2/NiS2 hybrid nanocrystals showed an onset potential of 911 mV and a half‐wave potential of 640 mV.In addition,the reversible oxygen electrode activity of the silk‐like FeS2/NiS2 hybrid nanocrystals was calculated to be 0.823 V,based on the potential of the OER and ORR.Further,the homemade rechargeable Zn‐air batteries using FeS2/NiS2 hybrid nanocrystals as the air‐cathode displayed a high open‐circuit voltage of 1.25 V for more than 17 h and an excellent rechargeable performance for 25 h.The solid Zn‐air batteries exhibited an excellent rechargeable performance for 15 h.This study provided a new method for designing interface nanocrystals with a unique morphology for efficient multifunctional electrocatalysts in electrochemical reactions and renewable energy devices.展开更多
CdS nanosheets(NSs)photocatalysts modified with dual earth‐abundant co‐catalysts of metallic carbon black(CB)and NiS2were synthesized by a two‐step solvothermal/impregnation method.Allthe experiment results demonst...CdS nanosheets(NSs)photocatalysts modified with dual earth‐abundant co‐catalysts of metallic carbon black(CB)and NiS2were synthesized by a two‐step solvothermal/impregnation method.Allthe experiment results demonstrated that the co‐loading of CB and NiS2could significantly enhance the photocatalytic H2‐evolution activity of CdS NSs.The photocatalytic performance of the as‐prepared CdS/CB/NiS2samples was tested under visible light(λ≥420nm)by using an aqueous solution containing0.25mol L–1Na2S‐Na2SO3as the sacrifice agent.The CdS‐0.5%CB‐1.0%NiS2composite photocatalysts exhibited the highest H2‐evolution rate of166.7μmol h?1,which was approximately5.16and1.87times higher than those of pure CdS NSs and CdS‐1.0%NiS2,respectively.The possible mechanism for the enhanced H2‐evolution activity of CdS/CB/NiS2composite photocatalysts was proposed.The results showed that the enhanced photocatalytic H2‐evolution activities could be ascribed to the co‐loading of metallic CB and NiS2as co‐catalysts onto the surface of CdS NSs.The excellent synergetic effect between the CB and NiS2could obviously improve visible light absorption,promote separation of photogenerated electron‐hole pairs and boost the H2‐evolution kinetics,thus leading to an enhanced activity for H2evolution.More interestingly,the metallic CB could not only act as a cocatalyst for H2evolution,but also serve as a conductive electron bridge to promote the charge migration.This work not only demonstrates that loading CB as a co‐catalyst is a promising strategy to further boost the photocatalytic activity of CdS/NiS2composites,but also offers a new mechanistic insight into the construction of highly efficient and stable CdS NSs‐based hybrid photocatalysts with dual earth‐abundant co‐catalysts for photocatalytic applications.展开更多
Electrocatalytic synthesis of value-added chemicals is attracting significant research attention owing to its mild reaction conditions, environmental benignity, and potentially scalable application to organic syntheti...Electrocatalytic synthesis of value-added chemicals is attracting significant research attention owing to its mild reaction conditions, environmental benignity, and potentially scalable application to organic synthetic chemistry. Herein, we report the preparation of a single-crystalline NiS2 nanostructure film of N 50 nm thickness grown directly on a carbon fiber doth （NiSJCFC） by a facile vapor-phase hydrothermal （VPH） method. NiSJCFC as an electrocatalyst exhibits activity for both the oxygen evolution reaction （OER） and the hydrogen evolution reaction （HER） in alkaline media. Furthermore, a series of alcohols （2-propanol, 2-butanol, 2-pentanol, and cyclohexanol） were electrocatalytically converted to the corresponding ketones with high selectivity, efficienc and durability using the NiSJCFC electrode in alkaline media. In the presence of 0.45 M alcohol, a remarkably decreased overpotential （- 150 mV, vs. RHE） at the NiS2/CFC anode compared with that for water oxidation to generate O2, i.e., the OER, in alkaline media leads to significantly improved H2 generation. For instance, the H2 generation rate in the presence of 0.45 M 2-propanol is almost 1.2-times of that obtained for pure water splitting, but in a system that employs an applied voltage at least 280 mV lower than that required for water splitting to achieve the same current density （20 mA-crn-2）. Thus, our results demonstrate the applicability of our bifunctional non-precious-metal electrocatalyst for organic synthesis and simultaneous H2 production.展开更多
Nickle sulfides are attractive anode materials for sodium-ion batteries(SIBs) due to their rich structures and natural abundance. However, their applications are greatly hindered by the large volume expansion and poor...Nickle sulfides are attractive anode materials for sodium-ion batteries(SIBs) due to their rich structures and natural abundance. However, their applications are greatly hindered by the large volume expansion and poor cycling properties. The introduction of hollow structures and heteroatom-doped carbon layers are effective ways to solve these issues. Here, nitrogen, sulfur co-doped carbon coated Ni3S2(abbreviated as, Ni3S2@NSC) nanotubes were prepared by a novel templating route. During the annealing process, NiS2 acts as both a precursor to Ni3S2 and an S-doped sulfur source.No additional sulfur source was used during the S-doping procedure, suggesting an atomically economic synthesis process. As anodes for sodium-ion half-cells, Ni3S2@NSCs exhibited high discharge capacity of 481 mA h g^-1 at 0.1 A g^-1 after 100 cycles with exceptional capacity retention of 98.6%.Furthermore, they maintained excellent rate capability of 318 mA h g^-1 even at elevated current density of 5 A g^-1. Sodium-ion full-cells assembled from the Ni3S2@NSC anodes and Na3V2(PO4)3(NVP@C) cathodes also presented superior capacities and cyclabilities. These features can be attributed to the N, S co-doped carbon coated hollow structure that provided sufficient contact between the electrode and electrolyte,enhanced surface ion storage performance(capacitive effect),and improved structural stability of electrode materials.展开更多
基金supported by the National Natural Science Foundation of China (21277107, 21477094, 51672203, 51472192)the Program for New Century Excellent Talents in University (NCET-13-0944)the Fundamental Research Funds for the Central Universities (WUT 2015IB002)~~
文摘NiS2 is a promising cocatalyst to improve the photocatalytic performance of g-C3N4 for the production of H2.However,the synthesis of the NiS2 cocatalyst usually requires harsh conditions,which risks destroying the microstructures of the g-C3N4 photocatalysts.In this study,a facile and low-temperature（80 ℃） impregnation method was developed to prepare NiS2/g-C3N4 photocatalysts.First,the g-C3N4 powders were processed by the hydrothermal method in order to introduce oxygen-containing functional groups（such as-OH and-C0NH-） to the surface of g-C3N4.Then,the Ni^2＋ ions could be adsorbed near the g-C3N4 via strong electrostatic interaction between g-C3N4 and Ni^2＋ ions upon the addition of Ni（NO3）2 solution.Finally,NiS2 nanoparticles were formed on the surface of g-C3N4 upon the addition of TAA.It was found that the NiS2 nanoparticles were solidly and homogeneously grafted on the surface of g-C3N4,resulting in greatly improved photocatalytic H2production.When the amount of NiS2 was 3 wt%,the resultant NiS2/g-C3N4 photocatalyst showed the highest H2 evolution rate（116.343 μmol h^-1 g^-1）,which is significantly higher than that of the pure g-C3N4（3 μmol h^-1 g^-1）.Moreover,the results of a recycling test for the NiS2/g-C3N4（3 wt%）sample showed that this sample could maintain a stable and effective photocatalytic H2-evolution performance under visible-light irradiation.Based on the above results,a possible mechanism of the improved photocatalytic performance was proposed for the presented NiS2/g-C3N4 photocatalysts,in which the photogenerated electrons of g-C3N4 can be rapidly transferred to the NiS2 nanoparticles via the close and continuous contact between them;then,the photogenerated electrons rapidly react with H2O adsorbed on the surface of NiS2,which has a surficial metallic character and high catalytic activity,to produce H2.Considering the mild and facile synthesis method,the presented low-cost and highly efficient NiS2-modified g-C3N4 photocatalysts would have great potential for practical use in photocatalytic H2 production.
基金supported by the National Basic Research Program of China(21571089,21503102,51571125)the Fundamental Research Funds for the Central Universities(lzujbky-2016-k02,lzujbky-2018-k08,lzujbky-2017-it42)~~
文摘The development of highly active and stable reversible oxygen electrocatalysts is crucial for improving the efficiency of metal‐air battery devices.Herein,an efficient liquid exfoliation strategy was designed for producing silk‐like FeS2/NiS2 hybrid nanocrystals with enhanced reversible oxygen catalytic performance that displayed excellent properties for Zn‐air batteries.Because of the unique silk‐like morphology and interface nanocrystal structure,they can catalyze the oxygen evolution reaction(OER)efficiently with a low overpotential of 233 mV at j=10 mA cm?2.This is an improvement from the recently reported catalysts in 1.0 M KOH.Meanwhile,the oxygen reduction reaction(ORR)activity of the silk‐like FeS2/NiS2 hybrid nanocrystals showed an onset potential of 911 mV and a half‐wave potential of 640 mV.In addition,the reversible oxygen electrode activity of the silk‐like FeS2/NiS2 hybrid nanocrystals was calculated to be 0.823 V,based on the potential of the OER and ORR.Further,the homemade rechargeable Zn‐air batteries using FeS2/NiS2 hybrid nanocrystals as the air‐cathode displayed a high open‐circuit voltage of 1.25 V for more than 17 h and an excellent rechargeable performance for 25 h.The solid Zn‐air batteries exhibited an excellent rechargeable performance for 15 h.This study provided a new method for designing interface nanocrystals with a unique morphology for efficient multifunctional electrocatalysts in electrochemical reactions and renewable energy devices.
基金supported by the National Natural Science Foundation of China(51672089)the Science and Technology Planning Project of Guangdong Province(2015B020215011)the State Key Laboratory of Advanced Technology for Material Synthesis and Processing(Wuhan University of Technology)(2015-KF-7)~~
文摘CdS nanosheets(NSs)photocatalysts modified with dual earth‐abundant co‐catalysts of metallic carbon black(CB)and NiS2were synthesized by a two‐step solvothermal/impregnation method.Allthe experiment results demonstrated that the co‐loading of CB and NiS2could significantly enhance the photocatalytic H2‐evolution activity of CdS NSs.The photocatalytic performance of the as‐prepared CdS/CB/NiS2samples was tested under visible light(λ≥420nm)by using an aqueous solution containing0.25mol L–1Na2S‐Na2SO3as the sacrifice agent.The CdS‐0.5%CB‐1.0%NiS2composite photocatalysts exhibited the highest H2‐evolution rate of166.7μmol h?1,which was approximately5.16and1.87times higher than those of pure CdS NSs and CdS‐1.0%NiS2,respectively.The possible mechanism for the enhanced H2‐evolution activity of CdS/CB/NiS2composite photocatalysts was proposed.The results showed that the enhanced photocatalytic H2‐evolution activities could be ascribed to the co‐loading of metallic CB and NiS2as co‐catalysts onto the surface of CdS NSs.The excellent synergetic effect between the CB and NiS2could obviously improve visible light absorption,promote separation of photogenerated electron‐hole pairs and boost the H2‐evolution kinetics,thus leading to an enhanced activity for H2evolution.More interestingly,the metallic CB could not only act as a cocatalyst for H2evolution,but also serve as a conductive electron bridge to promote the charge migration.This work not only demonstrates that loading CB as a co‐catalyst is a promising strategy to further boost the photocatalytic activity of CdS/NiS2composites,but also offers a new mechanistic insight into the construction of highly efficient and stable CdS NSs‐based hybrid photocatalysts with dual earth‐abundant co‐catalysts for photocatalytic applications.
文摘Electrocatalytic synthesis of value-added chemicals is attracting significant research attention owing to its mild reaction conditions, environmental benignity, and potentially scalable application to organic synthetic chemistry. Herein, we report the preparation of a single-crystalline NiS2 nanostructure film of N 50 nm thickness grown directly on a carbon fiber doth （NiSJCFC） by a facile vapor-phase hydrothermal （VPH） method. NiSJCFC as an electrocatalyst exhibits activity for both the oxygen evolution reaction （OER） and the hydrogen evolution reaction （HER） in alkaline media. Furthermore, a series of alcohols （2-propanol, 2-butanol, 2-pentanol, and cyclohexanol） were electrocatalytically converted to the corresponding ketones with high selectivity, efficienc and durability using the NiSJCFC electrode in alkaline media. In the presence of 0.45 M alcohol, a remarkably decreased overpotential （- 150 mV, vs. RHE） at the NiS2/CFC anode compared with that for water oxidation to generate O2, i.e., the OER, in alkaline media leads to significantly improved H2 generation. For instance, the H2 generation rate in the presence of 0.45 M 2-propanol is almost 1.2-times of that obtained for pure water splitting, but in a system that employs an applied voltage at least 280 mV lower than that required for water splitting to achieve the same current density （20 mA-crn-2）. Thus, our results demonstrate the applicability of our bifunctional non-precious-metal electrocatalyst for organic synthesis and simultaneous H2 production.
基金supported by the National Natural Science Foundation of China (51772082, 51804106 and 51574117)the Natural Science Foundation of Hunan Province (2019JJ30002 and 2019JJ50061)the China Postdoctoral Science Foundation (2018T110822 and 2017M610495)
文摘Nickle sulfides are attractive anode materials for sodium-ion batteries(SIBs) due to their rich structures and natural abundance. However, their applications are greatly hindered by the large volume expansion and poor cycling properties. The introduction of hollow structures and heteroatom-doped carbon layers are effective ways to solve these issues. Here, nitrogen, sulfur co-doped carbon coated Ni3S2(abbreviated as, Ni3S2@NSC) nanotubes were prepared by a novel templating route. During the annealing process, NiS2 acts as both a precursor to Ni3S2 and an S-doped sulfur source.No additional sulfur source was used during the S-doping procedure, suggesting an atomically economic synthesis process. As anodes for sodium-ion half-cells, Ni3S2@NSCs exhibited high discharge capacity of 481 mA h g^-1 at 0.1 A g^-1 after 100 cycles with exceptional capacity retention of 98.6%.Furthermore, they maintained excellent rate capability of 318 mA h g^-1 even at elevated current density of 5 A g^-1. Sodium-ion full-cells assembled from the Ni3S2@NSC anodes and Na3V2(PO4)3(NVP@C) cathodes also presented superior capacities and cyclabilities. These features can be attributed to the N, S co-doped carbon coated hollow structure that provided sufficient contact between the electrode and electrolyte,enhanced surface ion storage performance(capacitive effect),and improved structural stability of electrode materials.
