Photocatalytic hydrogen production based on semiconductor photocatalysts has been considered as one of the most promising strategies to resolve the global energy shortage.Graphitic carbon nitride(g‐C3N4)has been a st...Photocatalytic hydrogen production based on semiconductor photocatalysts has been considered as one of the most promising strategies to resolve the global energy shortage.Graphitic carbon nitride(g‐C3N4)has been a star visible‐light photocatalyst in this field due to its various advantages.However,pristine g‐C3N4usually exhibits limited activity.Herein,to enhance the performance of g‐C3N4,alkali metal ion(Li+,Na+,or K+)‐doped g‐C3N4are prepared via facile high‐temperature treatment.The prepared samples are characterized and analyzed using the technique of XRD,ICP‐AES,SEM,UV‐vis DRS,BET,XPS,PL,TRPL,photoelectrochemical measurements,photocatalytic tests,etc.The resultant doped photocatalysts show enhanced visible‐light photocatalytic activities for hydrogen production,benefiting from the increased specific surface areas(which provide more active sites),decreased band gaps for extended visible‐light absorption,and improved electronic structures for efficient charge transfer.In particular,because of the optimal tuning of both microstructure and electronic structure,the Na‐doped g‐C3N4shows the most effective utilization of photogenerated electrons during the water reduction process.As a result,the highest photocatalytic performance is achieved over the Na‐doped g‐C3N4photocatalyst(18.7?mol/h),3.7times that of pristine g‐C3N4(5.0?mol/h).This work gives a systematic study for the understanding of doping effect of alkali metals in semiconductor photocatalysis.展开更多
Batch tests were carried out to study the possibility of hydrogen production from alkali-pre- treated sludge without seed and the pH dependency of hydrogen fermentation from alkali-pretreated sludge. Experimental resu...Batch tests were carried out to study the possibility of hydrogen production from alkali-pre- treated sludge without seed and the pH dependency of hydrogen fermentation from alkali-pretreated sludge. Experimental results showed that the sewage sludge with alkali-pretreatment could be successfully applied to biologically producing hydrogen without seed and extra-feed. The results also showed that the initial pH value of sewage sludge was an impor-tant factor throughout the hydrogen fermentation of alkali-pretreated sludge. The maximum hydrogen yield was obtained at initial pH value of 11.0 (14.4 mL·g VS-1). The hydrogen yield of alkali-pretreated sludge at alkaline initial pH value was much higher than that of acidic or neutral initial pH value. The op-timal pH value of hydrogen production from alkali- pretreated sludge was approximately 9.5. The con-sumption of hydrogen could be inhibited when the pH value of sludge was above 8.5. The change of hy-drogen yield at various initial pH values was similar to that of sludge SCOD. The change of sludge pH value was slow and acetate was the major component of volatile fatty acids produced in the process of hy-drogen production. The yield and the constitution of volatile fatty acids were sensitive to the initial pH value.展开更多
Corn stover pretreated by Ceriporiopsis subvermispora was used as substrate to enhance biogas production via solid state anaerobic digestion(SS-AD).Effects of temperature,inoculum volume and alkaline concentration on ...Corn stover pretreated by Ceriporiopsis subvermispora was used as substrate to enhance biogas production via solid state anaerobic digestion(SS-AD).Effects of temperature,inoculum volume and alkaline concentration on the biogas production profermance were investigated.The results showed that pretreatment of corn stover by C.subvermispora benefited the biogas production.The optimal conditions were temperature 35°C,inoculum 10:1(w/w)and adding 5.0%of alkali,under which the maximum productions were obtained for daily and cumulative biogas of 14.07 L/kg VS and 211.09 L/kg VS.During the SS-AD process,the total solids(TS)and volatile solid(VS)were significantly degraded.The volatile fatty acids(VFA)concentration increased to 106 mmol/L and alkalinity decreased by about 23%.The results collectively suggested that microbial-alkali pretreatment of corn stove combining mesophilic condition could be a promising way to produce biogas in SS-AD.展开更多
基金supported by the National Natural Science Foundation of of China(51472191,21407115,21773179)the Natural Science Foundation of Hubei Province of China(2017CFA031)the Opening Project of Key Laboratory of Optoelectronic Chemical Materials and Devices,Ministry of Education(JDGD-201509)~~
文摘Photocatalytic hydrogen production based on semiconductor photocatalysts has been considered as one of the most promising strategies to resolve the global energy shortage.Graphitic carbon nitride(g‐C3N4)has been a star visible‐light photocatalyst in this field due to its various advantages.However,pristine g‐C3N4usually exhibits limited activity.Herein,to enhance the performance of g‐C3N4,alkali metal ion(Li+,Na+,or K+)‐doped g‐C3N4are prepared via facile high‐temperature treatment.The prepared samples are characterized and analyzed using the technique of XRD,ICP‐AES,SEM,UV‐vis DRS,BET,XPS,PL,TRPL,photoelectrochemical measurements,photocatalytic tests,etc.The resultant doped photocatalysts show enhanced visible‐light photocatalytic activities for hydrogen production,benefiting from the increased specific surface areas(which provide more active sites),decreased band gaps for extended visible‐light absorption,and improved electronic structures for efficient charge transfer.In particular,because of the optimal tuning of both microstructure and electronic structure,the Na‐doped g‐C3N4shows the most effective utilization of photogenerated electrons during the water reduction process.As a result,the highest photocatalytic performance is achieved over the Na‐doped g‐C3N4photocatalyst(18.7?mol/h),3.7times that of pristine g‐C3N4(5.0?mol/h).This work gives a systematic study for the understanding of doping effect of alkali metals in semiconductor photocatalysis.
文摘Batch tests were carried out to study the possibility of hydrogen production from alkali-pre- treated sludge without seed and the pH dependency of hydrogen fermentation from alkali-pretreated sludge. Experimental results showed that the sewage sludge with alkali-pretreatment could be successfully applied to biologically producing hydrogen without seed and extra-feed. The results also showed that the initial pH value of sewage sludge was an impor-tant factor throughout the hydrogen fermentation of alkali-pretreated sludge. The maximum hydrogen yield was obtained at initial pH value of 11.0 (14.4 mL·g VS-1). The hydrogen yield of alkali-pretreated sludge at alkaline initial pH value was much higher than that of acidic or neutral initial pH value. The op-timal pH value of hydrogen production from alkali- pretreated sludge was approximately 9.5. The con-sumption of hydrogen could be inhibited when the pH value of sludge was above 8.5. The change of hy-drogen yield at various initial pH values was similar to that of sludge SCOD. The change of sludge pH value was slow and acetate was the major component of volatile fatty acids produced in the process of hy-drogen production. The yield and the constitution of volatile fatty acids were sensitive to the initial pH value.
基金This work was financially supported by State Grid Science and Technology Program(No.SGECS 56-2014)China Ministry of Science and Technology(No.2014DFG32550)+1 种基金International Foundation for Science Grant Program(No.F 4930-1F/4930-2F).
文摘Corn stover pretreated by Ceriporiopsis subvermispora was used as substrate to enhance biogas production via solid state anaerobic digestion(SS-AD).Effects of temperature,inoculum volume and alkaline concentration on the biogas production profermance were investigated.The results showed that pretreatment of corn stover by C.subvermispora benefited the biogas production.The optimal conditions were temperature 35°C,inoculum 10:1(w/w)and adding 5.0%of alkali,under which the maximum productions were obtained for daily and cumulative biogas of 14.07 L/kg VS and 211.09 L/kg VS.During the SS-AD process,the total solids(TS)and volatile solid(VS)were significantly degraded.The volatile fatty acids(VFA)concentration increased to 106 mmol/L and alkalinity decreased by about 23%.The results collectively suggested that microbial-alkali pretreatment of corn stove combining mesophilic condition could be a promising way to produce biogas in SS-AD.
