查看更多>>摘要：It is an ideal route to generate hydrogen peroxide (H2O2) via selective 2e(-) ORR powered directly by sunlight. In this work, we synthesized a metal-free N-doped gamma-graphyne catalyst and wired it with n-type semiconductor photoanodes. The introduction of sunlight could lower the onset bias of oxygen reduction reaction (ORR) up to 0.32 V and H2O2 was steadily produced without any sacrificial agents and bias. The 2e(-) ORR selectivity of N-doped gamma-graphyne catalyst was bias dependent, and it reached about 74% at 0 bias in 0.1 mol.L-1 KOH. Theoretical calculations showed that in-situ pyridinic-N in N-doped gamma-graphyne acted as the active site for ORR, accelerating the rate-determining step of proton abstraction. The H2O2 yield reached as high as 7.47 mmol.h(-1) g(-1), outperformed the reported traditional photocatalytic syntheses of H2O2.
查看更多>>摘要：The visible light absorbing CdS nanoparticles were partially modified with Au2S and Ag2S via a simple cation exchange process to prepare hetemstructure photocatalysts (denoted as Au2S@CdS and Ag2S@CdS), which were employed for the conversion of aromatic alcohols to valued-added products, such as benzaldehyde and C-C coupling products, including deoxybenzoin and hydrobenzoin. When Au 2 S@CdS was used as the photocatalyst, benzaldehyde was obtained as the main product with a selectivity of 99%, and when Ag2S@CdS was used as the photocatalyst, deoxybenzoin was obtained as the main product with a selectivity of 95%. The critical photo-generated electron and hole transfer occurring during the photocatalytic reaction was systemically investigated by performing various control experiments and using in-situ high-resolution X-ray photoelectron spectroscopy. In addition, with the photocatalytic system proposed in this study, benzyl alcohol could be photoconverted into benzaldehyde or deoxybenzoin almost completely with high selectivity by altering the cocatalyst component via simple ion exchange.
查看更多>>摘要：Reductive catalytic conversion of DDT (p,p'-dichlorodiphenyltrichloroethane) was studied under ambient conditions in a hydrogen atmosphere using platinum and palladium deposited on several supports, in particular on porous alumina and silica. Almost complete hydrodechlorination and hydrogenation of DDT and its dehydrochlorination byproduct DDE (p,p' -dichlorodiphenyldichloroethene), leading to the formation of diphenylethane (with Pd) and dicyclohexylethane (with Pt), were observed at ambient temperature within minutes or hours. Rapid hydrodechlorination also takes place after depositing DDT and the metal component on separate particles and mixing them mechanically. This long-range reactivity can be explained either by a fast surface diffusion of DDT or DDE, or by hydrogen spillover. Irrespective of the mechanism, the reactivity thus bridges the barrier across solid particle interfaces. Most findings indicate the fast diffusion of target compounds as dominant mechanism for the observed long-range reactivity.
查看更多>>摘要：Three-dimensional flower-shaped plasmon Ag/Na-doped defective graphitic carbon nitride/NiFe layered double hydroxides (Ag/NaCNN/NiFe-LDH) Z-scheme heterojunction are fabricated by hydrothermal and calcination methods. The flower-shaped structure of NiFe-LDH enhances the multiple reflection and scattering of light, providing enough active sites to improve the utilization of sunlight. The introduction of Na-doped defects narrows the band gap of graphitic carbon nitride and accelerated the charge separation. Due to the surface plasmon resonance effect of Ag, Ag/NaCNN/NiFe-LDH shows excellent photothermal effect. The synergistic effect of photothermal-photocatalytic-Fenton reaction and Z-scheme heterojunction increased the hydrogen production of Ag/NaCNN/NiFe-LDH by 0.543 mmol h(-1), which was 10 times higher than that of NiFe-LDH. The degradation efficiency of p-nitrophenol and bisphenol A under visible light was 99%. This simple strategy and reasonable design provide new ideas for the construction of Z-scheme heterojunction photocatalysts.
Fierro-Gonzalez, Juan C.Solis-Garcia, AlfredoZepeda, Trino A.
10页
查看更多>>摘要：ZrO2-supported rhodium nanoparticles prepared by impregnation of RhCl3 are active for CO2 methanation at temperatures above 180 degrees C. Infrared (IR) spectra recorded during catalysis allowed identification of Rh carbonyls and formate species bonded to the support. To verify their individual involvement in the catalysis, their transformations were investigated by IR spectra measured as a sample of ZrO2-supported Rh was treated with CO and isotopically labelled formic acid. The data indicate two coexisting reaction routes: a dissociative route in which CO2 reacts on the Rh sample to give Rh carbonyls, and an associative route in which the CO2 molecule is activated on the support, in the form of bicarbonate species that are hydrogenated to give formate species prior to methane formation. Our data show that labelled formates are transformed into Rh-13CO, thus connecting the dissociative and associative catalytic routes. The results indicate the existence of a dual mechanism for CO2 methanation.
Chun, HojeHan, ByungchanShanmugam, SangarajuYesudoss, David Kumar...
10页
查看更多>>摘要：Electrochemical ammonia synthesis through the atmospheric nitrogen reduction reaction (NRR) is a promising method for sustainable fertilizer and carbon-free hydrogen energy carriers. The inevitable selectivity gap against hydrogen evolution reaction and inert nitrogen (N-2) hinders the device-level usage of nitrogen cathodes. In this work, we report engineered electrocatalyst/support interface of NbTiO4 nanoparticles supported on nitrogen doped carbon nanorods (NbTiO4@NCNR) to catalyze NRR. Insisted by the pitfalls to rationally design N-2 reduction catalysts, the strong catalyst-support interaction strategy is adapted to tune the selectivity towards NRR. Electrochemical tests reveal that NbTiO4@NCNR hybrid accelerates a 10-fold increase in N-2 selectivity compared to pure metal oxide. Using first-principles calculations, we identify the underlying mechanism of enhanced performance: bridging bonds in the interface as electron transport channels to promote the N-2 reduction kinetics. Essentially, this study provides an insight into how to overcome the immense kinetic barrier of NRR using smartly engineered interfaces of hybrid materials.
查看更多>>摘要：Ammonia is an indispensable chemical to the ecosystem and human beings. Storing solar energy in N-H bonds in NH3 is a promising sustainable alternative to the energy-consuming Haber Bosch process. However, nitrogen photofixation with this strategy still suffers from several unsolved issues, such as high-energy consumption with carbon footprint, short lifetime of photocatalysts, and nitrogen contamination in redox reactions. In this study, a room-temperature strategy is developed to two-dimensionally assemble the diminutive CoO-Co3O4 mixed-oxide composites on reduced graphene oxide. They proffer great surface area and deep-red-light absorbing defect states, which enable them to exhibit over 14 times higher photoactivity than template-free single components. The unveiled photoreaction-induced cation oxidation is reversely triggerable by photo-reactivating Co3O4 back to active CoO, with well-maintained photoactivity after six-cycles. All these room-temperature processes, from catalyst synthesis, nitrogen photofixation, to catalyst reactivation, offer facile way towards upscaling and hold great promise for practical zero-emission N-2 photofixation.
查看更多>>摘要：In this study, the catalytic performance of helical-form carbon fiber cloth anode loaded with atomic Fe@MoS2 (Fe@MoS2/CFC (h)) in piezocatalytic fuel cell (Pz-FC), improved 1.27 times with aeration as the piezo-driving force. The above Pz-FC with 0.5 mM peroxymonosulfate (PMS) and Xe-lamp irradiation forming a PMS-piezophotocatalytic fuel cell (PMS-Pz-PFC) system, removed 92.8% berberine in 60 min and generated power density that were respectively 2.04-fold and 8-fold higher than the PMS-Pz-PFC using MoS2/CFC (h) as the anode. Experiments showed that atomic Fe promoted piezo-photocatalysis of the helical-design anode significantly to accelerate the activation of PMS. Moreover, with 0.5 mM PMS, remarkable enhancement of electricity generation (more than 500 times difference) and pollutant degradation (by 40-50%) were achieved. The drastic synergy of piezoelectric catalysis in enhanced advanced oxidation has great practical application potential.
查看更多>>摘要：Solar-induced overall water splitting to produce hydrogen is inspiring towards energy sustainability, but it is also formidable due to its limited efficiency seriously hindering its scale up for practical application. CdS is an important transition metal sulfide with low-work-function. However, its photostability is often deteriorated due to photocorrosion influence. To overcome this issue, single-atom Pd was employed here to decorate CdS to form a CdS-Pd nanocatalyst through a simple and controllable photoinduced reduction strategy. The synergetic semiconductor (CdS)-metal (Pd) interaction promotes the fast bulk-to-surface electron migration, thereby the resultant CdS-Pd (3.83 parts per thousand) nanocatalyst shows considerable structural stability and dramatically improved solar induced HER activity in overall water splitting, about 110-fold higher than that of pristine CdS. Meanwhile, high apparent quantum yields (AQYs) of 4.47%/1.81% and 33.92%/27.49% were respectively achieved with this decorated nanocatalyst under the light of 420 nm/500 nm in absence and presence of scavenger, demonstrating the high-efficiency under broadband light illumination. Density functional theory (DFT) calculation supports that the easy formation of H* intermediates on the decorated nanocatalyst due to low energy barriers accounts for the internal promoted mechanism for hydrogen production. This study provides important insight to gain stable CdSbased photocatalysts for high-efficient hydrogen production by overall water splitting.
查看更多>>摘要：Co-based compounds have been considered as promising earth-abundant electrocatalysts for water splitting, however, the catalytic performance need to be further enhanced. Herein, we report a nickel foam (NF) supported Co-VOx-P nanoflower electrocatalyst that shows excellent catalytic performances, achieving a small over potential of 230 mV at 100 mA/cm(2) for OER. Such performances surpass the recently reported best-performing Co-based catalysts in alkaline media. In addition, the present Co-VOx-P electrocatalyst can deliver 10 mA/cm(2) with a small overpotential of 98 mV for HER. Experimental and DFT studies indicate that, due to the combination of P and V, the Co-VOx-P electrocatalyst shows improved intrinsic catalytic properties including enhanced conductivity, facile electron transfer and favorable surface adsorption strength. The strategy demonstrated here by incorporating metalloid with high valence states may be extended to design other cost-efficient electrocatalysts for more advanced water splitting performances.
NSTL
Elsevier