查看更多>>摘要：The methane dry reforming reaction (DRM) converts methane and CO2 into syngas, a mixture of H-2 and CO. When illuminated by 790 mW cm(-2) of white light, the 2Ni/CeO2-x catalyst converts CH4 and CO2 beyond thermodynamic equilibrium, while the energy efficiency reaches 33%. The DRM reaction is sustained in a purely photocatalytic mode without external heating, yielding CH4 and CO2 rates of 0.21 and 0.75 mmol (g(cat).min)(-1), respectively. Theoretical analysis of Ni/CeO2-x optical properties agrees with in-situ UV-Vis DRS results and reveals partly reduced Ce3+ sites crucial for extending the optical absorption of Ni/CeO2-x into the visible light range. Two photocatalytic mechanisms are postulated to occur: the hot charge-carrier driven photocatalytic mechanism and the near-field induced resonant energy transfer, depending on the energy of photons used to stimulate the catalyst. This work identifies sub-stoichiometric Ni/CeO2-x as highly efficient for boosting methane activation by visible light under mild conditions.
查看更多>>摘要：Pharmaceuticals and personal care products (PPCPs) are a large class of emerging contaminants. Here, we develop a 2D/2D Mo2C/g-C3N4 Van der Waals (VDW) heterojunction photocatalyst for typical PPCPs degradation. The 2D Mo2C shows unique electronic transport properties and allows the integration with other 2D materials for fabricating intriguing 2D interface. The Mo2C strongly coordinates with g-C3N4 to endow the ordered in-plane electron migration in g-C3N4 nanosheets and the VDW forces induce the electrons transfer within interlayers, building an internal electric field and stimulating the photogenerated charge kinetics. In addition, Mo2C can ameliorate the light absorption capacity and trap electrons to elongate the lifetimes of charge carriers. This synergy between VDW heterojunction and 2D structure engineering contributes to the superior photo catalytic activity for tetracycline degradation. Advanced characterizations, charge density based on density function theory calculations and the absence of charge transfer between layers confirm the VDW interactions between the individual components. This work provides a highly efficient and green strategy for typical PPCPs removal, and sheds lights on the construction of 2D/2D VDW heterojunction photocatalysts.
查看更多>>摘要：In this study, we propose a novel photo-activation method to remove persistent organic pollutants through a SO4--based advanced oxidation process. Core-shell Ag@Pd nanocubes were prepared by a facile seed-mediated method and, afterward, explored for photodegradation of a representative ionic liquid (IL), [C(4)mim]Br. Electron paramagnetic resonance measurements and radical scavenging experiments demonstrated that the species mainly responsible for degrading [C(4)mim]Br were the radicals of SO4-. The plasmon-mediated nature of the Ag@Pd catalysts was verified by their wavelength-dependent performance. Subsequent optical simulation indicated that, other than the plasmonic Ag core, the non-plasmonic Pd shell was the preferential site for dissipating the absorbed photons into energetic charge carriers to produce the radical species. Finally, based on the detected intermediates, we propose the degradation pathway of ILs in the plasmon-mediated process. The results of our method suggest favorable application in the treatment of wastewater.
查看更多>>摘要：Platinum-based catalysts play an important role in electrochemical hydrogen evolution reaction, which is a renewable and clean way to produce H-2. Herein, we have successfully synthesized the ultrafine PtNiP NWs with diameter less than 5 nm via a simple two-step hydrothermal reaction method. Impressively, the PtNiP NWs exhibit one of the best electrocatalytic activity toward HER under alkaline conditions, which can reach current density of 500 mA cm(-2) only at the -0.153 V vs RHE with Tafel slop of only 30 mV dec(-1). The DFT calculation results show synergistic effect of Pt, Ni and P atoms, where Ni atoms are conducive to the adsorption of H2O and P atoms are helpful for the dissociation of H2O, significantly improving kinetic processes of hydrogen evolution reaction. This work could be instructive and meaningful to design highly efficient and stable HER catalyst in alkaline condition for practical applications.
查看更多>>摘要：Visible-driven photocatalysis plays a critical role in solar energy conversion, but the efficiency is limited by the poor charge separation and utilization. Here, a ternary photocatalyst is constructed using Cu-In-Zn-S quantum dots (CIZS QDs), MoS2 and carbon dots (CDs). Interestingly, transient photovoltage measurements confirm that MoS2 has no assistance on the charge extraction rate, whereas CDs dramatically increases the attenuation constant of the charge recombination process (from 0.178 to 0.260 ms) due to its electron sinking effect. The optimal hydrogen production rate of CIZS/MoS2/CDs reaches 3706 mu mol g-1 h-1, which is 6.65 and 148.24 times to that of CIZS QDs and MoS2, respectively. Further electrocatalytic tests indicate that MoS2 is the main place for hydrogen evolution reaction, whereas CIZS and CDs are responsible for light harvesting and charge sinking, respectively. This work provides a useful guideline for the synergy of charge extraction and utilization process in composite photocatalyst design.
查看更多>>摘要：The generation of H+ by active species attacking proton donor (PD) is a key step in photocatalytic H2O2 production (PHP). Deeply analyzing the involved mechanism may be a crucial factor to break through the bottleneck of H2O2 yield. Here, nitrogen-deficient and boron-doped g-C3N4 are synthesized for PHP and the interaction mechanisms between active species and PD are revealed. The prepared photocatalyst exhibits a high H2O2 production rate (455 mu M h-1 g-1). The 1O2, center dot O2- and hole promoted by modification site dominate twelve different reaction mechanisms, respectively. For the oxidation pathways dominated by hole, H2O2 generation is limited by the dissociation of PD or desorption of H+ on catalyst surface. Interestingly, center dot O2- and 1O2 could directly attack PD, or diffuse into solution to react with PD to produce H2O2 with lower barriers. Moreover, there is a synergistic effect between doped-boron, 1O2 and water bridge, which further reduces the reaction barrier.
查看更多>>摘要：The excellent optoelectronic properties of metal halide perovskites (MHPs) have been employed in various photocatalytic applications, but their poor water stability is considered as the main bottleneck for further development. Herein, we protect the light-absorbing CsPbBr3 MHP with a NiOx and TiO2 hole and electron extracting layer. This planar NiOx/CsPbBr3/TiO2 architecture can easily be fabricated through solutionprocessing. When applied to selective photocatalytic oxidation of benzyl alcohol, this system presents a 7-fold enhancement of photoactivity and an improved stability for over 90 h compared to CsPbBr3 counterpart. Interestingly, we find that trace amounts of water improve photoactivity. Through experimental and theoretical analyses, this improvement could be attributed to water-induced structural reorganization of MHP, leading to improved crystal quality and decreased effective masses of charge carriers. This work indicates planar heterojunction helps improve the photoactivity and stability of MHP photocatalyst, and our findings provide insights into the effect of water on MHPs.
查看更多>>摘要：The advancement of cost-effective nanostructured catalysts for the electrochemical reduction of CO2 to valuable chemicals is of great interest. In the present study, cobalt-oxide nanodendrites were directly grown on a Co substrate and systemically studied towards the electrochemical reduction of CO2. Our electrochemical measurements revealed that the formed Co nanodendrites exhibited superb catalytic activity in comparison to the Cobased catalysts reported in the literature, with a small onset potential (-0.2 V vs RHE) and an extremely high current density for the CO2 reduction. In situ electrochemical attenuated total reflection Fourier transform infrared spectroscopy was employed to elucidate the reduction reaction mechanism, revealing that the formation of formate at the Co nanodendrites proceeded through the formation of a carbon-bound adsorbed *COO- intermediate. The innovative approach and the in-situ FTIR analysis reported in the present study would provide insights in the design and tuning of advanced electrocatalysts for energy and environmental applications.
查看更多>>摘要：The exploration of an efficient electrocatalyst for the oxygen evolution reaction (OER) is urgently required for sustainable renewable-energy conversion and storage. Due to the increased chemical complexity, multimetallic catalysts provide flexibility to alter their electronic and crystal structure to attain a superior intrinsic catalytic activity via synergistic effects, which is seldom accomplished using single metal catalysts. However, the high chemical complexity increases the difficulty to prepare elemental homogenous catalysts and reveal their synergistic effect during OER process, which further hinder the design of multimetallic catalysts. Here, high entropy concept is utilized to design an NiFeCoMnAl oxide with amorphous structure as OER catalyst. The direct evidence of active Ni sites is provided by the operando Raman measurements and Fe can modify oxygen intermediates binding energy on Ni sites. The X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) reveal that the incorporation of Mn can construct the electron-rich environment of active Ni center, and the relatively lower oxidation state of Ni facilitates the self-construction of beta-NiOOH intermediates, which shows promoted OER activity as confirmed by density functional theory calculations. Doping Co can enhance the conductivity and doping Al leads to the formation of nanoporous structure through dealloying process, thus each component is essential for improving OER performance. The optimized NiFeCoMnAl catalyst exhibits an overpotential of 190 mV at 10 mA cm(-2) in 1 M KOH solution, much superior to the ternary and quaternary counterparts. This work sheds light on understanding the origin of high entropy catalysts' OER activity and thereby enables the rational design of multinary transition metallic catalysts.
查看更多>>摘要：Exploitation of catalysts with multi-active sites is very important for enhancing catalytic performance. 0D/2D hybrids, especially quantum dots (QDs)/nanosheets (NSs), have attracted increasing attentions for advanced oxidation processes due to high charge mobility and more active sites. However, 0D/2D hybrids with multi-active sites still remain a great challenge. Herein, 0D Cu-Fe bi-metal oxide QDs/2D g-C3N4 (CNNSs) exhibiting superior advantages beyond single-metal 0D/2D counterparts was fabricated via a facile one-step synthesis strategy for photo-Fenton catalysis. The synergy of ultrafine Cu-Fe sites on CNNSs led to outstanding tetracycline removal efficiency over a wide pH range. Our experiments and DFT calculations clearly demonstrated that except for the fast charge separation and transfer, this synergy could achieve the optimal H2O2 adsorption-activation trade-off on Cu-Fe sites, while also modify tetracycline absorption, leading to multiple synergies of adsorption-catalytic degradation and photocatalysis-Fenton oxidation. This work provides new insights in developing multi-functional 0D/2D hybrids for environment and energy applications.
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Elsevier