Prior to the installation of the Cd-liner in one of the large outer irradiation channels of NIRR-1, a Monte Carlo simulation was performed using MCNP5 version 1.4 code. This was done to investigate the effect of insta...Prior to the installation of the Cd-liner in one of the large outer irradiation channels of NIRR-1, a Monte Carlo simulation was performed using MCNP5 version 1.4 code. This was done to investigate the effect of installation of Cd-liner in either an inner or outer irradiation channel on reactor physics parameters. Data obtained indicate that the core excess reactivity in both inner and outer irradiations channels is reduced by 3.60 ± 0.07 mk and 0.64 ± 0.06 mk, respectively. Considering the fact that NIRR-1 has a cold core excess reactivity of 3.77 mk, results obtained show that installation of the 1 mm thick Cd-sheet in one of the large outer irradiation channels would have no significant impact on the core physics data. After installation of a 1 mm Cd sheath in a large outer irradiation channel, the neutron flux distribution and the stability in the irradiation channels were monitored by foil activation method. Results indicate that the uniformity of neutron flux distribution in the irradiation channel is preserved and the neutron flux data were found to be comparable with the data obtained before the installation.展开更多
Photoelectrochemical nitrate reduction reaction(PEC-NIRR)is a promising technology of nitrogen fixation,which has the advantages of mild conditions and small carbon footprint.However,due to the low selectivity and com...Photoelectrochemical nitrate reduction reaction(PEC-NIRR)is a promising technology of nitrogen fixation,which has the advantages of mild conditions and small carbon footprint.However,due to the low selectivity and competitive hydrogen evolution reaction(HER),PEC-NIRR still faces a critical challenge to achieve the efficient production of NH_(3).For the first time,in this study,Ce-doped p-BiVO_(4) was fabricated and applied to PEC-NIRR.Ce^(3+)mainly replaced the Bi^(3+)sites in the p-BiVO_(4) matrix,and the reversible redox ability of Ce effectively promoted internal carrier migration and surface catalytic kinetics.Without the externally applied potentials(0 V vs.RHE),1.5%Ce-BiVO_(4) showed desirable activity,and the NH_(3) yield of 1.5%Ce-BiVO_(4) reached 31.54μg h^(-1) cm^(-2),which is 3.9 times that of p-BiVO_(4).The selectivity of NH3(relative to NO_(2)-)was enhanced to 24.5 times,compared with that of pristine p-BiVO_(4).In addition,1H nuclear magnetic resonance(1H NMR)spectroscopy verified that the source of N was entirely NO3-.Therefore,this work identifies the critical role of Ce sites for tailoring the nature of p-BiVO_(4) for efficient PEC-NIRR.展开更多
The photoelectrochemical nitrate reduction reaction(PEC-NIRR)provides a sustainable solution for addressing nitrogen-containing wastewater pollution and green ammonia synthesis.However,the reported catalysts are still...The photoelectrochemical nitrate reduction reaction(PEC-NIRR)provides a sustainable solution for addressing nitrogen-containing wastewater pollution and green ammonia synthesis.However,the reported catalysts are still limited by issues such as low carrier separation efficiency and competition from the hydrogen evolution reaction(HER).A surface sulfidation strategy was employed to epitaxially grow Bi_(2)S_(3)in situ on the surface of CuBi_(2)O_(4),successfully constructing a CuBi_(2)O_(4)/Bi_(2)S_(3)catalyst.Based on the narrow bandgap(1.67 eV)and sulfur atom active sites of Bi_(2)S_(3),a type II band arrangement and atomic level contact were configured.The oxygen vacancy(Ov)concentration could be regulated to 48.98%,significantly promoting charge separation and the generation of hydrogen radicals(H*).Under illumination,CuBi_(2)O_(4)/Bi_(2)S_(3)achieves a high NH_(3)production rate of 33.69μg h^(−1)cm^(−2),which is 3.84 times that of CuBi_(2)O_(4).The by-product NO_(2)−production rate was significantly suppressed,contributing to an excellent selectivity(59.71%).FTIR and 1H NMR spectroscopic analyses further confirmed that NH3 generation was entirely derived from NO_(3)^(−).Therefore,this work offers a novel strategy of in situ sulfidation for boosting the intrinsic activity of polymetallic oxide catalysts.展开更多
文摘Prior to the installation of the Cd-liner in one of the large outer irradiation channels of NIRR-1, a Monte Carlo simulation was performed using MCNP5 version 1.4 code. This was done to investigate the effect of installation of Cd-liner in either an inner or outer irradiation channel on reactor physics parameters. Data obtained indicate that the core excess reactivity in both inner and outer irradiations channels is reduced by 3.60 ± 0.07 mk and 0.64 ± 0.06 mk, respectively. Considering the fact that NIRR-1 has a cold core excess reactivity of 3.77 mk, results obtained show that installation of the 1 mm thick Cd-sheet in one of the large outer irradiation channels would have no significant impact on the core physics data. After installation of a 1 mm Cd sheath in a large outer irradiation channel, the neutron flux distribution and the stability in the irradiation channels were monitored by foil activation method. Results indicate that the uniformity of neutron flux distribution in the irradiation channel is preserved and the neutron flux data were found to be comparable with the data obtained before the installation.
基金the National Natural Science Foundation of China(22075112)Jiangsu Province and Education Ministry Co-sponsored Synergistic Innovation Center of Modern Agricultural Equipment(XTCX2027).
文摘Photoelectrochemical nitrate reduction reaction(PEC-NIRR)is a promising technology of nitrogen fixation,which has the advantages of mild conditions and small carbon footprint.However,due to the low selectivity and competitive hydrogen evolution reaction(HER),PEC-NIRR still faces a critical challenge to achieve the efficient production of NH_(3).For the first time,in this study,Ce-doped p-BiVO_(4) was fabricated and applied to PEC-NIRR.Ce^(3+)mainly replaced the Bi^(3+)sites in the p-BiVO_(4) matrix,and the reversible redox ability of Ce effectively promoted internal carrier migration and surface catalytic kinetics.Without the externally applied potentials(0 V vs.RHE),1.5%Ce-BiVO_(4) showed desirable activity,and the NH_(3) yield of 1.5%Ce-BiVO_(4) reached 31.54μg h^(-1) cm^(-2),which is 3.9 times that of p-BiVO_(4).The selectivity of NH3(relative to NO_(2)-)was enhanced to 24.5 times,compared with that of pristine p-BiVO_(4).In addition,1H nuclear magnetic resonance(1H NMR)spectroscopy verified that the source of N was entirely NO3-.Therefore,this work identifies the critical role of Ce sites for tailoring the nature of p-BiVO_(4) for efficient PEC-NIRR.
基金supported by the National Natural Science Foundation of China(22075112)the College Student Practice Innovation Training Program Project(3221306040)the Open Project Funded by Key Laboratory of Green Extraction&Efficient Utilization of Light Rare-Earth Resources,Ministry of Education(KLRE-KF-007).
文摘The photoelectrochemical nitrate reduction reaction(PEC-NIRR)provides a sustainable solution for addressing nitrogen-containing wastewater pollution and green ammonia synthesis.However,the reported catalysts are still limited by issues such as low carrier separation efficiency and competition from the hydrogen evolution reaction(HER).A surface sulfidation strategy was employed to epitaxially grow Bi_(2)S_(3)in situ on the surface of CuBi_(2)O_(4),successfully constructing a CuBi_(2)O_(4)/Bi_(2)S_(3)catalyst.Based on the narrow bandgap(1.67 eV)and sulfur atom active sites of Bi_(2)S_(3),a type II band arrangement and atomic level contact were configured.The oxygen vacancy(Ov)concentration could be regulated to 48.98%,significantly promoting charge separation and the generation of hydrogen radicals(H*).Under illumination,CuBi_(2)O_(4)/Bi_(2)S_(3)achieves a high NH_(3)production rate of 33.69μg h^(−1)cm^(−2),which is 3.84 times that of CuBi_(2)O_(4).The by-product NO_(2)−production rate was significantly suppressed,contributing to an excellent selectivity(59.71%).FTIR and 1H NMR spectroscopic analyses further confirmed that NH3 generation was entirely derived from NO_(3)^(−).Therefore,this work offers a novel strategy of in situ sulfidation for boosting the intrinsic activity of polymetallic oxide catalysts.
