负载有CuO的La_2Ti_2O_7的光催化还原水制氢性能研究

通过浸渍法制备了负载有CuO的La2Ti2O7(CuO/La2Ti2O7),并对其紫外光催化还原水制氢性能进行了研究。结果表明,当以甲醇作为牺牲剂时,在紫外光照射下CuO/La2Ti2O7是一个高活性的光解水制氢催化剂。CuO的负载量为5%(mol/mol)时,产氢速率可达54.7μmol/(h.g)。在光催化过程中,CuO所起的作用是促进电荷的分离并成为产氢的活性位点。实验结果还表明在CuO/La2Ti2O7催化体系中,CuO是一个良好的助催化剂,完全有可能替代Ag、Pt等常用的贵金属助催化剂。这一研究结果为La2Ti2O7系催化剂在光解水制氢领域的实际应用提供了更为广阔的前景。

铌酸钾纳米管的制备及其光催化还原水制氢研究

以铌酸钾颗粒为前驱体,经酸化和剥落处理,在简单、温和的条件下制得铌酸钾纳米管。透射电镜结果表明,产物具有管状形貌,且管形完整、管径分布窄、长径比大。研究了铌酸钾纳米管在紫外光照射下的光催化还原水制氢性能,铌酸钾纳米管的活性明显高于铌酸钾颗粒,负载Pt的铌酸钾纳米管的制氢活性明显提高,在pH=3的10%(体积分数)甲醇水溶液中负载1.5%铂的铌酸钾纳米管的产氢活性(18.8 mmol/g.h)最高,是铌酸钾纳米管负载前(0.385 mmol/(g.h))的48.8倍。

A review on TiO_2-based Z-scheme photocatalysts

TiO2‐based Z‐scheme photocatalysts have attracted considerable attention because of the low recombination rate of their photogenerated electron–hole pairs and their high photocatalytic efficiency.In this review,the reaction mechanism of Z‐scheme photocatalysts,recent research progress in the application of TiO2‐based Z‐scheme photocatalysts,and improved methods for photocatalytic performance enhancement are explored.Their applications,including water splitting,CO2reduction,decomposition of volatile organic compounds,and degradation of organic pollutants,are also described.The main factors affecting the photocatalytic performance of TiO2‐based Z‐scheme photocatalysts,such as pH,conductive medium,cocatalyst,architecture,and mass ratio,are discussed.Concluding remarks are presented,and some suggestions for the future development of TiO2‐based Z‐scheme photocatalysts are highlighted.

"Environmental phosphorylation"boosting photocatalytic CO_(2)reduction over polymeric carbon nitride grown on carbon paper at air-liquid-solid joint interfaces

The limited CO_(2)content in aqueous solution and low adsorption amount of CO_(2)on catalyst surface lead to poor photocatalytic CO_(2)reduction activity and selectivity.Herein,the design and fabrication of a novel photocatalytic architecture is reported,accomplished via chemical vapor deposition of polymeric carbon nitride on carbon paper.The as-obtained samples with a hydrophobic surface exhibit excellent CO_(2)transport and adsorption ability,as well as the building of triphase air-liquid-solid(CO_(2)-H_(2)O-catalyst)joint interfaces,eventually resulting in the inhibition of H2 evolution and great promotion of CO_(2)reduction with a selectivity of 78.6%.The addition of phosphate to reaction environment makes further improvement of CO_(2)photoreduction into carbon fuels with a selectivity of 93.8%and an apparent quantum yield of 0.4%.This work provides new insight for constructing efficient photocatalytic architecture of CO_(2)photoreduction in aqueous solution and demonstrates that phosphate could play a key role in this process.

Amorphous CoOx coupled carbon dots as a spongy porous bifunctional catalyst for efficient photocatalytic water oxidation and CO2 reduction

Cobalt-based oxides,with high abundance,good stability and excellent catalytic performance,are regarded as promising photocatalysts for artificial photosynthetic systems to alleviate foreseeable energy shortages and global warming.Herein,for the first time,a series of novel spongy porous CDs@CoOx materials were synthesized to act as an efficient and stable bifunctional photocatalyst for water oxidation and CO2 reduction.Notably,the preparation temperatures visibly influence the morphologies and photocatalytic performances of the CDs@CoOx.Under the optimal conditions,a maximum O2 yield of 40.4% and pretty apparent quantum efficiency(AQE)of 58.6% at 460 nm were obtained over CDs@CoOx-300 for water oxidation.Similarly,the optimized sample CDs@CoOx-300 manifests significant enhancement on the CO2-to-CO conversion with a high selectivity of 89.3% and CO generation rate of 8.1μmol/h,which is superior to most previous cobalt-based catalysts for CO2 reduction.The composite CDs@CoOx-300 not only exposes more active sites but also facilitates electron transport,which results in excellent photocatalytic activity.In addition,the boosted photocatalytic behavior is attributed to the synergistic effect between CoOx and CDs,which was verified by the photocatalytic activity control experiments and electrochemical characterization.The work offers a novel strategy to fabricate a high performance bifunctional photocatalyst for water oxidation and CO2 reduction.

Development of a bismuth-based metal-organic framework for photocatalytic hydrogen production

A novel 3 D bismuth-organic framework(called Bi-TBAPy) single crystal was synthesized by employing 1,3,6,8-tetrakis(p-benzoic acid)pyrene(H4TBAPy) as an organic linker. The study demonstrates that the Bi-TBAPy not only possesses good chemical stability and suitable band edge positions for promising photocatalytic H2 evolution, but it also exhibits a typical ligand-to-metal charge transfer for favorable charge separation. The photocatalytic H2 evolution rates on the as-obtained Bi-TBAPy with different cocatalysts modified were examined with triethanolamine as the sacrificial reagent. Based on this, the hydrogen evolution rate of 140 μmol h-1 g-1 was obtained on the optimized sample with a loading of 2 wt% Pt as a cocatalyst. To the best of our knowledge, this is the first bismuth-based metal-organic framework(MOF) that functions as an effective photocatalyst for photocatalytic water reduction. Our study not only adds a new member to the family of photocatalyst materials, but also reveals the importance of cocatalyst modification in improving photocatalytic activity of MOFs.

Interfacial engineering of graphitic carbon nitride(g-C_3N_4)-based metal sulfide heterojunction photocatalysts for energy conversion: A review

As one of the most appealing and attractive technologies, photocatalysis is widely used as a promising method to circumvent the environmental and energy problems. Due to its chemical stability and unique physicochemical, graphitic carbon nitride (g-C3N4) has become research hotspots in the community. However, g-C3N4 photocatalyst still suffers from many problems, resulting in unsatisfactory photocatalytic activity such as low specific surface area, high charge recombination and insufficient visible light utilization. Since 2009, g-C3N4-based heterostructures have attracted the attention of scientists worldwide for their greatly enhanced photocatalytic performance. Overall, this review summarizes the recent advances of g-C3N4-based nanocomposites modified with transition metal sulfide (TMS), including (1) preparation of pristine g-C3N4,(2) modification strategies of g-C3N4,(3) design principles of TMS-modified g-C3N4 heterostructured photocatalysts, and (4) applications in energy conversion. What is more, the characteristics and transfer mechanisms of each classification of the metal sulfide heterojunction system will be critically reviewed, spanning from the following categories:(1) Type I heterojunction,(2) Type II heterojunction,(3) p-n heterojunction,(4) Schottky junction and (5) Z-scheme heterojunction. Apart from that, the application of g-C3N4-based heterostructured photocatalysts in H2 evolution, CO2 reduction, N2 fixation and pollutant degradation will also be systematically presented. Last but not least, this review will conclude with invigorating perspectives, limitations and prospects for further advancing g-C3N4-based heterostructured photocatalysts toward practical benefits for a sustainable future.

Interfacial coupling effects in g-C_(3)N_(4)/In_(x)Sb_(2-x)S_(3) heterojunction for enhanced photocatalytic activity under visible light

A series of In_(x)Sb_(2-x)S_(3) nanosheets modified g-C_(3)N_(4)(In_(x)Sb_(2-x)S_(3)-TCN)heterojunctions with different g-C_(3)N_(4) contents were fabricated by an in situ deposition method.All the In_(x)Sb_(2-x)S_(3)-TCN composites were applied as photocatalysts in Cr(Ⅵ)polluted water treatment and the results displayed that In_(x)Sb_(2-x)S_(3)-TCN could effectively remove Cr(Ⅵ)under visible light through synergistic effects of adsorption and photocatalytic reduction.Especially,In_(x)Sb_(2-x)S_(3)-TCN-70(70 mg g-C_(3)N_(4)) exhibited the most excellent adsorption and photocatalytic reduction performance among all composites,which possessed a high equilibrium adsorption capacity of 12.45 mg/g in a 30.0 mg/L Cr(Ⅵ)aqueous solution,and reduced Cr(Ⅵ)to Cr(Ⅲ)within 10 min under visible light irradiation.DRS and PL results indicated that the interfacial coupling effect between g-C_(3)N_(4)and In_(x)Sb_(2-x)S_(3) enhanced the utilization efficiency of visible light and suppressed photoinduced carrier recombination,which improved the photocatalytic activity of composites.Moreover,the photocatalyst exhibited satisfactory reduction activity and good stability after 5 cycles of Cr(Ⅵ)adsorptionphotoreduction.