Conventional hexagonal dimolybdenum carbide(Mo2 C) as a good cocatalyst has been widely applied for the enhanced photocatalytic hydrogen production of various photocatalysts. Compared with the hexagonal Mo2 C, however...Conventional hexagonal dimolybdenum carbide(Mo2 C) as a good cocatalyst has been widely applied for the enhanced photocatalytic hydrogen production of various photocatalysts. Compared with the hexagonal Mo2 C, however, the investigation about cubic molybdenum carbide(Mo C) is still very limited in photocatalytic field. In this study, carbon-coated cubic molybdenum carbide(MoC@C) nanoparticle was synthesized and used as an effective cocatalyst to improve the H2-evolution efficiency of Ti O2. The cubic MoC@C can be obtained by adjusting the mass ratio of C3 N3(NH2)3 to(NH4)6 Mo7 O(24)(2:1) and controlling the calcination temperature to 800 °C. When the above cubic MoC@C nanoparticles were evenly loaded on the Ti O2 via a sonication-assisted deposition, a homogeneous composite of TiO2/MoC@C was formed due to the strong coupling interface between TiO2 and cubic MoC nanoparticles. More importantly, the highest H2-production rate of Ti O-12/MoC@C reached 504 μmol hg^(-1)(AQE=1.43%), which was 50 times as high as that of the pure TiO2. The enhanced performance of TiO2/MoC@C can be attributed to the synergistic effect of carbon layer as an electron mediator and the cubic MoC as interfacial H2-evolution active sites. This work provides a feasible guideline to develop high-efficiency Mo-based cocatalysts for potential applications in the H2-evolution field.展开更多
Traditional bulk MoS_(2) as an effective H_(2)-evolution cocatalyst is mainly subjected to the weak hydrogen-adsorption ability of highporpotion saturated S,resulting in a slow interfacial H_(2)-evolution reaction.In ...Traditional bulk MoS_(2) as an effective H_(2)-evolution cocatalyst is mainly subjected to the weak hydrogen-adsorption ability of highporpotion saturated S,resulting in a slow interfacial H_(2)-evolution reaction.In this paper,an efficient strategy for enhancing hydrogen adsorption of saturated S by manipulating electron density through O atoms is proposed to boost photocatalytic performance of CdS.Simultaneously,amorphization of MoS_(2) can further increase the unsaturated active S sites.Herein,oxygencontained amorphous MoS_(x)(a-MoOS_(x))nanoparticles(10-30 nm)were tightly loaded on the CdS surface through a mild photoinduced deposition method by using(NH_(4))_(2)[MoO(S_(4))_(2)]solution as the precursor at room temperature.The photocatalytic H_(2)-evolution result showed that the a-MoOS_(x)/CdS performed the superior H_(2)-production activity(382μmol·h^(-1),apparent quantum efficiencies(AQE)=11.83%)with a lot of visual H_(2)bubbles,which was 54.6,2.5,and 5.1 times as high as that of CdS,MoS_(x)/CdS,and annealed a-MoOS_(x)/CdS,respectively.Characterizations and density functional theory(DFT)calculations revealed the mechanism of improved H_(2)-evolution activity is that the O heteroatom in amorphous MoOS_(x) can enhance the atomic H-adsorption ability by manipulating the electron density to form electron-deficient S^((2-δ)-)sites.This study provides a new idea to improve the efficiency and number of H_(2)-evolution active sites for developing efficient cocatalysts in the field of photocatalytic hydrogen evolution.展开更多
Hexagonal molybdenum carbide(Mo_(2)C)as an effective non-noble cocatalyst is intensively researched in the photocatalytic H_(2)-evolution field owing to its Pt-like H^(+)-adsorption ability and good conductivity.Howev...Hexagonal molybdenum carbide(Mo_(2)C)as an effective non-noble cocatalyst is intensively researched in the photocatalytic H_(2)-evolution field owing to its Pt-like H^(+)-adsorption ability and good conductivity.However,hexagonal Mo_(2)C-modified photocatalysts possess a limited H_(2)-evolution rate because of the weak H-desorption ability.Tofurther improve the activity,cubic MoC was introduced into Mo_(2)C toform the carbon-modified MoC-Mo_(2)C nanoparticles(MoC-Mo_(2)C@C)by a calcination method.The resultant MoC-Mo_(2)C@C(ca.5 nm)was eventually coupled with Ti0_(2)to acquire high-efficiency Ti0_(2)/MoC-Mo_(2)C@C by electrostatic self-assembly.The highest H_(2)-generation rate of Ti0_(2)/MoC-Mo_(2)C@C reached of 918μmol·h^(-1)·g^(-1)which was 91.8,2.7,and 1.5 times than that of the Ti0_(2),TiO_(2)/MoC@C,and Ti0_(2)/Mo_(2)C@C,respectively.The enhanced rate of Ti0_(2)attributes to the carbon layer as cocatalyst to transmit electrons and the hetero-phase MoC-Mo_(2)C as H_(2)-generation active sites to boost H_(2)-evolution reaction.This research offers a novel insight to design photocatalytic materials for energy applications.展开更多
Exploiting efficient and low-cost cocatalyst with a facile grafting strategy is of critical importance for significantly boosting the photocatalytic H2-evolution activity.In this study,S2^--adsorbed MoSx nanoparticle ...Exploiting efficient and low-cost cocatalyst with a facile grafting strategy is of critical importance for significantly boosting the photocatalytic H2-evolution activity.In this study,S2^--adsorbed MoSx nanoparticle as a superior H2-evolutoin cocatalyst was successfully grafted on the TiO2 surface to greatly boost its photocatalytic activity via one-step lactic acid-induced synthesis strategy.Herein,the lactic acid can induce the homogeneous production of amorphous MoSx(a-MoSx)nanoparticles from MoS42-precursor,while the symbiotic S2^-ions can be easily and availably self-adsorbed on the a-Mo Sxsurface,resulting in the formation of S2^--adsorbed a-Mo Sxnanoparticles with a small size of 0.5-3 nm.Photocatalytic results manifested that the S2^--adsorbed Mo Sxnanoparticles could dramatically facilitate the H2-generation rate of TiO2 photocatalysts(3452μmol h^-1 g^-1,AQE=16.5%).In situ irradiated XPS in conjunction with transient-state PL and photoelectrochemical tests reveal that the improved H_(2)-generation activity can be ascribed to the synergistic effect of boosted interfacial charge transfer from TiO_(2) to S^(2-)adsorbed Mo Sx and the superior H_(2)-evolution reaction on self-adsorbed S_(2-)ions.In addition,the S^(2-)-adsorbed Mo Sx nanoparticles can also act as the general H_(2)-generation cocatalyst to obviously promote the activity of other typical host photocatalysts such as g-C_(3) N_(4) and Cd S.This work provides an innovative approach to develop high-efficiency Mo Sx-based cocatalyst with boosted interfacial charge transfer toward highly efficient photocatalytic materials.展开更多
CdS photocorrosion is one of the most important factors that greatly affect the photocatalytic H_(2)-production rate and long-time stability.However,the reported works about CdS photocorrosion are mainly focused on th...CdS photocorrosion is one of the most important factors that greatly affect the photocatalytic H_(2)-production rate and long-time stability.However,the reported works about CdS photocorrosion are mainly focused on the surface oxidation by photogenerated holes,while the possible reduction of lattice Cd^(2+) by photogenerated electrons is usually ignored.In this work,the lattice Cd^(2+) reduction by photogenerated electrons during CdS photocorrosion were carefully investigated to reveal its potential effect on the microstructure change and photocatalytic H_(2)-production performance of CdS photocatalyst based on the two typical Na_(2)S-Na_(2)SO_(3) and lactic acid H_(2)-evolution systems.It was found that many isolated metallic Cd nanoparticles(5–50 nm)were produced on the CdS surface in the Na_(2)S-Na_(2)SO_(3) system,causing its serious destroy of CdS surface and a gradually decreased photocatalytic activity,while only a metallic Cd layer(2-3 nm)is homogeneously coated on the CdS surface in the lactic acid system,leading to an increased H-evolution rate.In fact,once a certain amount of metallic Cd was produced on the CdS surface,the resulting CdS-Cd composites can present a stable photocatalytic H_(2)-production activity and excellent stability for the final CdS-Cd photocatalysts.Hence,a photoinduced self-stability mechanism of CdS photocatalyst has been proposed,namely,the spontaneously produced metallic Cd contributes to the transformation of unstable CdS into stable CdS-Cd structure,with the simultaneous realization of final stable H_(2)-evolution performance.展开更多
基金supported by the National Natural Science Foundation of China (51872221 and 21771142)the Fundamental Research Funds for the Central Universities (WUT 2019IB002)。
文摘Conventional hexagonal dimolybdenum carbide(Mo2 C) as a good cocatalyst has been widely applied for the enhanced photocatalytic hydrogen production of various photocatalysts. Compared with the hexagonal Mo2 C, however, the investigation about cubic molybdenum carbide(Mo C) is still very limited in photocatalytic field. In this study, carbon-coated cubic molybdenum carbide(MoC@C) nanoparticle was synthesized and used as an effective cocatalyst to improve the H2-evolution efficiency of Ti O2. The cubic MoC@C can be obtained by adjusting the mass ratio of C3 N3(NH2)3 to(NH4)6 Mo7 O(24)(2:1) and controlling the calcination temperature to 800 °C. When the above cubic MoC@C nanoparticles were evenly loaded on the Ti O2 via a sonication-assisted deposition, a homogeneous composite of TiO2/MoC@C was formed due to the strong coupling interface between TiO2 and cubic MoC nanoparticles. More importantly, the highest H2-production rate of Ti O-12/MoC@C reached 504 μmol hg^(-1)(AQE=1.43%), which was 50 times as high as that of the pure TiO2. The enhanced performance of TiO2/MoC@C can be attributed to the synergistic effect of carbon layer as an electron mediator and the cubic MoC as interfacial H2-evolution active sites. This work provides a feasible guideline to develop high-efficiency Mo-based cocatalysts for potential applications in the H2-evolution field.
基金This work was supported by the National Natural Science Foundation of China(No.22178275)the Natural Science Foundation of Hubei Province of China(No.2022CFA001).
文摘Traditional bulk MoS_(2) as an effective H_(2)-evolution cocatalyst is mainly subjected to the weak hydrogen-adsorption ability of highporpotion saturated S,resulting in a slow interfacial H_(2)-evolution reaction.In this paper,an efficient strategy for enhancing hydrogen adsorption of saturated S by manipulating electron density through O atoms is proposed to boost photocatalytic performance of CdS.Simultaneously,amorphization of MoS_(2) can further increase the unsaturated active S sites.Herein,oxygencontained amorphous MoS_(x)(a-MoOS_(x))nanoparticles(10-30 nm)were tightly loaded on the CdS surface through a mild photoinduced deposition method by using(NH_(4))_(2)[MoO(S_(4))_(2)]solution as the precursor at room temperature.The photocatalytic H_(2)-evolution result showed that the a-MoOS_(x)/CdS performed the superior H_(2)-production activity(382μmol·h^(-1),apparent quantum efficiencies(AQE)=11.83%)with a lot of visual H_(2)bubbles,which was 54.6,2.5,and 5.1 times as high as that of CdS,MoS_(x)/CdS,and annealed a-MoOS_(x)/CdS,respectively.Characterizations and density functional theory(DFT)calculations revealed the mechanism of improved H_(2)-evolution activity is that the O heteroatom in amorphous MoOS_(x) can enhance the atomic H-adsorption ability by manipulating the electron density to form electron-deficient S^((2-δ)-)sites.This study provides a new idea to improve the efficiency and number of H_(2)-evolution active sites for developing efficient cocatalysts in the field of photocatalytic hydrogen evolution.
基金supported by the National Natural Science Foundation of China(21771142 and 51672203)the Fun-damental Research Funds for the Central Universities(WUT 2019IB002)。
基金the National Natural Science Foundation of China(Nos.51872221,21771142)the Fundamental Research Funds for the Central Universities(No.WUT2019IB002).
文摘Hexagonal molybdenum carbide(Mo_(2)C)as an effective non-noble cocatalyst is intensively researched in the photocatalytic H_(2)-evolution field owing to its Pt-like H^(+)-adsorption ability and good conductivity.However,hexagonal Mo_(2)C-modified photocatalysts possess a limited H_(2)-evolution rate because of the weak H-desorption ability.Tofurther improve the activity,cubic MoC was introduced into Mo_(2)C toform the carbon-modified MoC-Mo_(2)C nanoparticles(MoC-Mo_(2)C@C)by a calcination method.The resultant MoC-Mo_(2)C@C(ca.5 nm)was eventually coupled with Ti0_(2)to acquire high-efficiency Ti0_(2)/MoC-Mo_(2)C@C by electrostatic self-assembly.The highest H_(2)-generation rate of Ti0_(2)/MoC-Mo_(2)C@C reached of 918μmol·h^(-1)·g^(-1)which was 91.8,2.7,and 1.5 times than that of the Ti0_(2),TiO_(2)/MoC@C,and Ti0_(2)/Mo_(2)C@C,respectively.The enhanced rate of Ti0_(2)attributes to the carbon layer as cocatalyst to transmit electrons and the hetero-phase MoC-Mo_(2)C as H_(2)-generation active sites to boost H_(2)-evolution reaction.This research offers a novel insight to design photocatalytic materials for energy applications.
基金financially supported by the National Natural Science Foundation of China(Nos.51872221 and 21771142)the Fundamental Research Funds for the Central Universities(No.WUT 2019IB002)。
文摘Exploiting efficient and low-cost cocatalyst with a facile grafting strategy is of critical importance for significantly boosting the photocatalytic H2-evolution activity.In this study,S2^--adsorbed MoSx nanoparticle as a superior H2-evolutoin cocatalyst was successfully grafted on the TiO2 surface to greatly boost its photocatalytic activity via one-step lactic acid-induced synthesis strategy.Herein,the lactic acid can induce the homogeneous production of amorphous MoSx(a-MoSx)nanoparticles from MoS42-precursor,while the symbiotic S2^-ions can be easily and availably self-adsorbed on the a-Mo Sxsurface,resulting in the formation of S2^--adsorbed a-Mo Sxnanoparticles with a small size of 0.5-3 nm.Photocatalytic results manifested that the S2^--adsorbed Mo Sxnanoparticles could dramatically facilitate the H2-generation rate of TiO2 photocatalysts(3452μmol h^-1 g^-1,AQE=16.5%).In situ irradiated XPS in conjunction with transient-state PL and photoelectrochemical tests reveal that the improved H_(2)-generation activity can be ascribed to the synergistic effect of boosted interfacial charge transfer from TiO_(2) to S^(2-)adsorbed Mo Sx and the superior H_(2)-evolution reaction on self-adsorbed S_(2-)ions.In addition,the S^(2-)-adsorbed Mo Sx nanoparticles can also act as the general H_(2)-generation cocatalyst to obviously promote the activity of other typical host photocatalysts such as g-C_(3) N_(4) and Cd S.This work provides an innovative approach to develop high-efficiency Mo Sx-based cocatalyst with boosted interfacial charge transfer toward highly efficient photocatalytic materials.
基金the National Natural Science Foundation of China(Nos.22075220 and 51872221)the 111 Project(No.B18038)。
文摘CdS photocorrosion is one of the most important factors that greatly affect the photocatalytic H_(2)-production rate and long-time stability.However,the reported works about CdS photocorrosion are mainly focused on the surface oxidation by photogenerated holes,while the possible reduction of lattice Cd^(2+) by photogenerated electrons is usually ignored.In this work,the lattice Cd^(2+) reduction by photogenerated electrons during CdS photocorrosion were carefully investigated to reveal its potential effect on the microstructure change and photocatalytic H_(2)-production performance of CdS photocatalyst based on the two typical Na_(2)S-Na_(2)SO_(3) and lactic acid H_(2)-evolution systems.It was found that many isolated metallic Cd nanoparticles(5–50 nm)were produced on the CdS surface in the Na_(2)S-Na_(2)SO_(3) system,causing its serious destroy of CdS surface and a gradually decreased photocatalytic activity,while only a metallic Cd layer(2-3 nm)is homogeneously coated on the CdS surface in the lactic acid system,leading to an increased H-evolution rate.In fact,once a certain amount of metallic Cd was produced on the CdS surface,the resulting CdS-Cd composites can present a stable photocatalytic H_(2)-production activity and excellent stability for the final CdS-Cd photocatalysts.Hence,a photoinduced self-stability mechanism of CdS photocatalyst has been proposed,namely,the spontaneously produced metallic Cd contributes to the transformation of unstable CdS into stable CdS-Cd structure,with the simultaneous realization of final stable H_(2)-evolution performance.
