查看更多>>摘要：In this study, we delicately design a novel iron-based dioxygen activation system for sustainable production of O-1(2) on iron phosphide (FeP). This is the first time to realize the( 1)O(2) production on Fe-based dioxygen activation. Unlike traditional iron-based materials that only activate dioxygen, this delicately designed FeP can simultaneously activate dioxygen and adsorb some generated center dot OH. Those center dot OH can react with O-2(center dot-)/HO2 center dot. Thus, the center dot OH-mediated reaction can in-situ occur on the surface of FeP to rapidly produce O-1(2). As a result, the FeP exhibits remarkably higher degradation activity for various organic pollutants and pollutants in real aquatic systems in absence of light, electricity and other oxidants. Therefore, this study provides a green strategy to generate( 1)O(2) for environmental remediation and also demonstrates a new role of surface-bound center dot OH in contributing to the O-1(2) production.
查看更多>>摘要：Coupling CO2 photoreduction with selective organic synthesis offers a promising modus operandi to enable simultaneous utilization of photogenerated electrons and holes to realize solar fuels production and chemicals synthesis. Herein, we report a bifunctional zero-dimensional cadmium sulfide quantum dots-two-dimensional titanium dioxide nanosheets (CdS/TNS) heterostructure for photoredox-catalyzed coupling of C-C bond synthesis via selective oxidation of benzyl alcohol with CO2 photoreduction to CO under visible light. The compositing heterointerface is beneficial for the adsorption and activation of CO2, thereby promoting the photoreduction of CO2. Remarkably, the synergistic interaction between CdS and TNS tunes the selectivity of benzyl alcohol oxidation from carbonyl compound to the C-C coupled products. Mechanistic studies unveil that the generation of C-C coupled products processes via key radical center dot CH(OH)Ph intermediates. Theoretical simulations reveal that the weaker adsorption of center dot CH(OH)Ph radical over CdS/TNS than bare CdS contributes to the formation of highly selective C-C coupled products. The findings are expected to offer instructive guidance on rationally designing the dual-functional catalysts with efficient photoredox-catalyzed coupling reaction systems for integrating CO2 reduction with selective organic transformations.
查看更多>>摘要：Designing a photocatalyst for hydrogen production is pivotal role in renewable energy technologies. Herein, the synthesis of nanosized NiSe2 particles via supercritical fluid process with the short reaction time of 30 min was reported. Then, it was used as a co-catalyst over TiO2 to improve H-2 production rate. Supercritical fluid process is an effective and alternative technique for nanoparticle preparation in short time. In the presence of NiSe2, the H-2 production rate of TiO2 was greatly increased thereby attained the maximum activity of 219.2 mmol/h/gcat with STH of 9% and is closer to that of Pt loaded TiO2 & nbsp;(9.7% for 235.5 mmol/h/gcat). The highly conductive nature of NiSe2 facilitates rapid transfer of photogenerated electrons from TiO2 to NiSe2. The detailed possible mechanism was debated and confirmed by first principles DFT calculations. This work validates short time reaction to prepare highly conductive NiSe(2 & nbsp;)as an electron sink for efficient H-2 production.
查看更多>>摘要：We steer the catalytic performance and morphology of Pd - lanthanum iron manganite (LFM) perovskite interfaces towards optimum NO+CO reactivity in presence of water by following different preparation approaches. Strong CO adsorption for samples without Pd-perovskite interface acts as an inhibitor for adsorption/dissociation of NO, while samples with an extended interface, additionally aided by H2O, show reduced CO poisoning. The optimized use of lattice oxygen for CO oxidation at the phase boundary and its replenishment from NO dissociation allows for the formation of more poisoning-resistant active sites for NO activation. Reaction of species from H2O dissociation with adsorbed CO assists further surface clean off. Enhanced NO reduction activity on the "de-poisoned" interface leads to a pronounced increase in N-2 selectivity. Preferred production of NH3 at low NO and high CO and H2O concentration indicates that water gas shift intermediates are linked to increased surface hydrogen activity and increased NH3 formation.
查看更多>>摘要：Conversion of CO2 to catalytically active carbons for electrochemical synthesis of hydroxide peroxide (H2O2) is highly desirable to replace the energy-intensive anthraquinone process, and achieve carbon utilization and emission reduction. Here, we develop an electrochemical reduction-reoxidation strategy in the in-situ conversion of absorbed CO2 to defective porous carbons (DPCs) for boosting H2O2 production. By rationally varying oxidation conditions, hole and edge defects were controllably created on CO2-derived carbons. Moreover, the defects dramatically enhanced the activity and selectivity toward the 2e- oxygen reduction reaction (ORR). DPC0.5-5 obtained by electro-oxidizing the CO2-derived carbon has edge and hole defects, delivering the H2O2 selectivity greater than 90%. By means of density functional theory calculations, the essential role of defects is demonstrated, and the types of defects with high activity are identified. The approach presented here not only sheds light on the value-added utilization of CO2, but also develops the defect engineering of carbon materials.
查看更多>>摘要：Direct Z-scheme heterojunction can primely facilitate separation efficiency of the photogenerated carriers and maximize the redox ability of as-prepared photocatalyst, which has been regarded as one of the promising strategies to increase photocatalytic CO(2 )conversion efficiency. Herein, a novel interfacial C-S bond modulated Z scheme heterojunction Bi19S27Br3/g-C(3)N(4 )composite is constructed to accelerate the photogenerated electron transfer from g-C3N4 to Bi19S27Br3, offering much more excited reductive electrons to the surface of Bi19S27Br3 where owns lower CO2 adsorption energy, which is more conducive to CO2 reduction conversion. Without adding sacrificial agent or photosensitizer, the photocatalytic CO(2 )conversion to CO yield of Bi19S27Br3/g-C3N4 reaches up to 12.87 mu mol g(-1) h(-1), which is 5 and 4-fold of Bi(19)S27Br(3 )and g-C3N4, respectively. This study provides the new insight in precisely tailoring photogenerated charge separation direction by establishing chemical bond in direct Z-scheme structure for CO(2 )photoreduction.
查看更多>>摘要：The fixation of CO2 with epoxides is a promising strategy to reduce CO2 emission. However, homogeneous halogen-based cocatalysts are often requisite for most heterogeneous catalysts to obtain desired activities, which significantly complicates the subsequent product purification/separation. Herein, we report the heterogenization of homogeneous Br-based cocatalysts by encapsulating them into stable and recyclable ZIF-8-based hollow nanoreactors (ZIF-8-HS) for efficient CO2 fixation. The synthesis involves in epitaxial growth of a size-controlled ZIF-8 layer on hollow ZIF-67 spheres prepared by using Br-contained surfactants as templates, followed by etching the unstable ZIF-67 shell. In ZIF-8-HS, the Br-contained surfactants can serve as efficient cocatalysts to activate substrates, while the microporous ZIF-8 shell possesses abundant intrinsic active sites and offers the cocatalysts a confined homogeneous environment. Impressively, ZIF-8-HS shows high activity, good size-selectivity and excellent recyclability for the CO2 fixation with epoxides, fully exploiting the respective advantages of homogeneous CTAB and heterogeneous ZIF-8 for this reaction.
查看更多>>摘要：Materials derived from MOFs have great potentials in energy conversion. However, the nanoscale transformation processes of MOFs derivatives remain unknown. Herein, by using in-situ liquid phase TEM, we directly visualize the MOFs etching processes. For the first time, unexpected nanobubble stability controlled transformation mechanism of ZIF-67 to porous or layered cobalt transition metal hydroxide (Co-TMH) is identified. Voids in MOFs migrate and merge to form nanobubbles due to structural collapse. Under slow diffusion conditions, nanobubbles move slowly and Co-TMH clusters generate on the nanobubble interface, further favoring the formation of internal nanocages and porous structures. On the other hand, a fast diffusion leads to rapid nanobubbles generation, aggregation and reshaping, inducing layered structure formation. Inspired by in-situ observation, we further synthesize porous Co-TMH at -80 degrees C under inhibited diffusion conditions, which exhibits excellent catalytic performance on CO2 reduction reaction.
查看更多>>摘要：A ternary dual Z-scheme composite gCN/ZnFe2O4/Bi2S3 (ZFO/BS) was synthesized via a facile microwave assisted process and its photocatalytic potential was explored towards visible light driven removal of 2,4,6-triboundFe(2+/3+)|(surf.),Zn+/2+|(surf.)andBi(3+/4+)|(surf.) were effective towards charge carrier channelization and evolution cholorophenol (TCP) with subsequent peroxymonosulfate (PMS) activation. Surface of reactive species. Highest catalytic activity was experienced for the catalyst with 10 wt% Bi2S3 (ZFO/BS(10)) and 98.9% TCP was removed with 0.25 gL-1 catalyst and 1.0 gL-1 PMS, under 60 mins visible light irradiation (intensity: 80 W). Construction of dual Z-scheme heterojunction was studied using XPS and the mechanism of e(-)/h(+) separation was elucidated. In-depth radical scavenging and EPR analysis confirmed the coexistence and relative contributions of various reactive radicals towards degradation. Plausible TCP degradation pathway was designed based on intermediate analysis. This study elucidates the superiority of dual Z-scheme ternary heterojunction towards separation of photogenerated charge carriers and mineralization of various emerging contaminants.
查看更多>>摘要：Regulating the directional migration of photo-generated carriers is an important strategy for realising highperformance photocatalysts. In this work, nano-particle Ni2P and peanut-like BiVO4 were grown on a rhombic structure Ni-MOF-74 substrate. A composite catalyst Ni-MOF-74/BiVO4/P with excellent performance was prepared by the high-temperature calcination method. Phosphorus modification produces Ni2P as an electron capture centre while maintaining the basic morphology of Ni-MOF-74, effectively avoiding the accumulation of nanoparticles. The Ni2P nanoparticles not only increase the number of active sites but also introduce negatively charged P that captures more protons for hydrogen evolution. After reasonable modification, the hydrogen production of the Ni-MOF-74/BiVO4/P reached 245.4 mu mol in 5 h, 23 times that of pure Ni-MOF-74. An S-scheme heterojunction between Ni-MOF-74 and BiVO4 achieves the directional transfer of carriers thereby inhibiting the recombination of electron-hole pairs. The band structure and density of states of Ni2P and BiVO4 were determined in density functional calculations. This work provides a new way for the regulation of the carrier behaviour in photocatalysts.
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Elsevier