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A green one-pot approach for mesoporous g-C3N4 nanosheets with in situ sodium doping for enhanced photocatalytic hydrogen evolution
摘要： Synchronous nano-structuring and element-doping of g-C3N4 were realized via a green one-pot approach to improve its photocatalytic activity. Na-doped mesoporous g-C3N4 nanosheets of ~5 nm in thickness were facilely synthesized by calcining a mixture of dicyandiamide and sodium chloride. NaCl not only serves as a con?ning-reactor to con?ne the growth of g-C3N4 into mesoporous nanosheets, but also acts as a sodium source for Na-doping. The nanosheets own greater speci?c surface area, stronger optical absorption and lower recombination of photo-induced electron-hole pairs than bulk g-C3N4, and exhibit an excellent visible-light photocatalytic hydrogen evolution ef?ciency which is about 13 times that of bulk g-C3N4. Moreover, the thermostable and hydrosoluble NaCl is simply removed and recycled by water and then directly reused in a new synthesis, making the process to be environmental-friendly and sustainable.
关键词： g-C3N4,Sodium chloride,Photocatalytic hydrogen evolution,Sodium doping,Mesoporous nanosheet
更新于2025-09-10 09:29:36
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Rational Design of Graphic Carbon Nitride Copolymers by Molecular Doping for Visible-Light-Driven Degradation of Aqueous Sulfamethazine and Hydrogen Evolution
摘要： Carbon nitride is a promising metal-free visible light driven photocatalyst and sustainable material for address contaminant pollution and water splitting. However, the insufficient visible light absorption and fast charge recombination of carbon nitride have limited its practical application. Herein, the self-assembly carbon nitride (denoted as TCN) by molecular doping copolymerization of urea and 2-thiobarbitucid acid (TA) was prepared. XPS and elemental analytical results indicated that TA was doped in the framework of carbon nitride successfully. The self-assembly copolymerization would result in the change of morphology, intrinsic electron and band structure of carbon nitride. Theoretical calculations and experiments confirm that the band gap of TCN could be adjusted by changing the amount of 2-thiobarbitucid acid. Moreover, the efficiency of charge carrier transfer and separation was greatly enhanced. As a result, the optimized photocatalyst TCN-0.03 exhibited superior activity with a high reaction rate of 0.058 min-1 for the degradation of sulfamethazine under visible light irradiation, which is 4.2 times higher than that of urea based carbon nitride (U-CN). As a multifunctional photocatalyst, TCN-0.03 showed enhanced activity for hydrogen production (55 μmol h-1), which was 11 times higher than U-CN. The apparent quantum efficiency reached to 4.8% at 420 nm. A possible mechanism was proposed to explain the photocatalytic reaction process. This work provides insight into the rational design of modified carbon nitride by other organic monomers copolymerization to enhance the photocatalytic activity.
关键词： Photocatalytic degradation,Photocatalytic hydrogen evolution,Carbon nitride,Charge carriers transfer,Molecular doping copolymerization
更新于2025-09-09 09:28:46
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Graphene based nanocomposites for efficient photocatalytic hydrogen evolution: insight into the interface toward separation of photogenerated charges
摘要： Although the reduced graphene oxide (rGO) has been intensively applied to photocatalytic H2 evolution, no enough attention was given to study the interface between photocatalyst and rGO, which is the key point to affect the transportation of photogenerated electron. Herein, in order to research the heterojunctions interface, the series of SrTiO3 photocatalysts with different crystal facets were fabricated to load with rGO for photocatalytic H2 evolution. The characterization measurements and theory calculation verified that the rGO was mainly anchored on the Ti-O bond of SrTiO3. So, compared to {001} facets sample, the {110} facets of SrTiO3, exposed more Ti and O atoms, could form stronger bond with the rGO. Additionally, DFT study deduced that the photoinduced electron could immigrate rapidly from Ti-O bond to the rGO, which was in good agreement with the results of photoelectrochemical and photoluminescence (PL) experiments. Meanwhile, experimentally, the 1 % wt. rGO@SrTiO3 with {110} facets nanocomposite showed the superior photocatalytic H2 yield rate (3.82 mmol/h/g), which was 2.2 times and 3.2 times higher than that of pure SrTiO3 with the same facets and 1 % wt. rGO@SrTiO3 with {001} facets, respectively. Both experiments and theoretical calculations unveiled that the synergetic effect of SrTiO3 facets engineering and rGO loading effectively prompted the immigration of photoinduced electron at the nanocomposites interface. This work provides a rational thinking of a high efficiency rGO-based heterogeneous photocatalysts for solar energy conversion.
关键词： density functional theory study,rGO-based heterogeneous photocatalysts,separation of photogenerated charges,photocatalytic hydrogen evolution,SrTiO3,electron screening effect
更新于2025-09-09 09:28:46
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Round-the-clock Photocatalytic Hydrogen Production with High Efficiency by a Long Afterglow Material
摘要： Long afterglow materials can store and release light energy after illumination. Here, a brick-like, micron-sized Sr2MgSi2O7:Eu2+,Dy3+ long afterglow material is used for hydrogen production via the photocatalytic reforming of methanol under round-the-clock conditions for the first time, achieving a solar-to-hydrogen (STH) conversion efficiency of 5.18%. This material is one of the most efficient photocatalysts and provides the possibility of practical use on a large scale. Its remarkable photocatalytic activity is attributed to its unique carrier migration path and large number of lattice defects. Our findings expand the application scope of long afterglow materials and provide a new strategy to design efficient photocatalysts by constructing trap levels that can prolong carriers’ lifetimes.
关键词： round-the-clock,water,Long afterglow,photocatalytic hydrogen evolution,methanol
更新于2025-09-09 09:28:46
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Round‐the‐clock Photocatalytic Hydrogen Production with High Efficiency by a Long Afterglow Material
摘要： Long afterglow materials can store and release light energy after illumination. Here, a brick-like, micron-sized Sr2MgSi2O7:Eu2+,Dy3+ long afterglow material is used for hydrogen production via the photocatalytic reforming of methanol under round-the-clock conditions for the first time, achieving a solar-to-hydrogen (STH) conversion efficiency of 5.18%. This material is one of the most efficient photocatalysts and provides the possibility of practical use on a large scale. Its remarkable photocatalytic activity is attributed to its unique carrier migration path and large number of lattice defects. Our findings expand the application scope of long afterglow materials and provide a new strategy to design efficient photocatalysts by constructing trap levels that can prolong carriers’ lifetimes.
关键词： round-the-clock,water,Long afterglow,photocatalytic hydrogen evolution,methanol
更新于2025-09-04 15:30:14
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Photocatalytic hydrogen evolution from water using fluorene and dibenzothiophene sulfone conjugated microporous and linear polymers
摘要： Three series of conjugated microporous polymers (CMPs) were studied as photocatalysts for hydrogen production from water using a sacrificial hole scavenger. In all cases, dibenzo[b,d]thiophene sulfone polymers outperformed their fluorene analogs. A porous network, S-CMP3, showed the highest hydrogen evolution rate of 6076 μmol h-1 g-1 (λ > 295 nm) and 3106 μmol h-1 g-1 (λ > 420 nm), with an external quantum efficiency of 13.2% at 420 nm. S-CMP3 outperforms its linear structural analog, P35, while in other cases, non-porous linear polymers are superior to equivalent porous networks. This suggests that microporosity might be beneficial for sacrificial photocatalytic hydrogen evolution, if suitable linkers are used that do not limit charge-transport and the material can be wetted by water as studied here by water sorption and quasi-elastic neutron scattering.
关键词： fluorene,sacrificial hole scavenger,conjugated microporous polymers,photocatalytic hydrogen evolution,dibenzo[b,d]thiophene sulfone
更新于2025-09-04 15:30:14
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Oxygen vacancy‐rich anatase TiO2 hollow spheres via liquid nitrogen quenching process for enhanced photocatalytic hydrogen evolution
摘要： Development of novel methods to obtain highly active catalysts for photocatalytic hydrogen evolution is desired. This work reports a facile preannealing-quenching strategy to synthesize oxygen vacancy-rich anatase TiO2 hollow spheres. TiO2 hollow spheres are first synthesized via a versatile kinetics-controlled coating method and then subjected to high temperature preannealing followed by rapid quenching in liquid-nitrogen (-196 oC). The as-quenched samples appear light grey suggesting the presence of abundant surface oxygen vacancies, which are subsequently confirmed by the comprehensive analyses of XRD, XPS and EPR spectra. The oxygen vacancies induced by quenching process are proved to have promoted the light adsorption and inhibited the recombination of photo-induced charges for TiO2 hollow spheres, which obviously improve the photocatalytic performance of those samples. The results showed that the TiO2 hollow spheres quenched at 500 oC exhibited a robust stability and the most excellent photocatalytic performance for hydrogen evolution (413.5 μmol·h-1) over other quenched samples and it displayed 1.51 times higher performance than that of samples normally cooled at 500 oC (273.7 μmol · h-1). Herein, this liquid-nitrogen quenching strategy presented here provides an effective route for the synthesis of high-performance TiO2 for water splitting and have a promising prospect in the other application.
关键词： quenching,hollow spheres,photocatalytic hydrogen evolution,oxygen defects,titanium dioxide
更新于2025-09-04 15:30:14
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Enhancement of visible‐light photocatalytic hydrogen production by CeCO3OH in g‐C3N4/CeO2 system
摘要： Promoting the separation of photo-generated carriers is significantly important to improve the efficiency of photocatalytic hydrogen production. Therefore, we prepared g-C3N4/CeCO3OH/CeO2 (CeCeCN) ternary nanocomposite via an easy synthetic way using g-C3N4 and CeO2 as reactants. A CeCO3OH layer was formed and resulted in the novel ternary photocatalyst. The CeCeCN composite shows superior photocatalytic (PC) H2 generation performance in sunlight excitation. The H2 evolution rate is about 764 μmol h-1 g-1, which is over 11 times larger than those of g-C3N4 and CeO2. Compared with g-C3N4 and CeO2, CeCeCN further shows a larger photo-response current density and a lower charge-transfer resistance. The remarkably increased photocatalytic property of CeCeCN is because of the efficient charge migration induced by the formed heterojunction. Our findings demonstrate that building multi-heterostructures can liberate more excited electrons for efficient hydrogen production under sunlight.
关键词： heterojunction,CeCO3OH,g-C3N4/CeCO3OH/CeO2,photocatalytic hydrogen evolution,ternary
更新于2025-09-04 15:30:14