查看更多>>摘要：Hydrogen evolution reaction (HER) in alkali involves higher energy barriers and slow reaction kinetics due to involving water dissociation process. Catalysts with proper surface properties are highly needed to optimize the surface binding energy with reaction intermediates and enhance intrinsic catalytic activity. Herein, we present an effective strategy to construct a self-standing catalyst with core-shell structure, which is composited of metallic Co nanoparticles coated by RuCo alloy layer with optimized surface properties. The Ru attracts electrons from Co and optimizes the surface electronic structure. Theoretical calculations demonstrate that the water dissociation barrier on the Co surface is decreased from 0.65 eV to 0.58 eV after alloying with Ru. Experimental results reveal that the synthesized Co@RuCo-3 features highly efficient catalytic activity together with good stability at large current densities for HER in alkali, as well as in alkaline seawater and pure seawater.
查看更多>>摘要：Graphene has long been considered to only transfer photo-generated electrons for H-2 production in photo catalytic H2O splitting, however this "common sense " is quite different in our research. Herein, spin polarized graphene monolayer-based van der Waals heterostructure was constructed by chemical vapor deposition on twodimensional MoS2. Theoretical and experimental results confirm that photogenerated e- and h+ are spatially separated and directionally transferred from MoS2 to the opposite regions of monolayer graphene to form "electric field " via. the van der Waals heterojunction under the spin polarized monolayer-graphene-induced polarization promotion, thus H-2 and O-2 generation can be simultaneously realized in the "electric field " under visible-light irradiation. In this case, photocatalytic H2O splitting has been transformed into a process similar to electrocatalytic H2O decomposition, as revealed by the mechanism calculation. This result updates the mechanism of photogenerated charge carrier transfer and photocatalysis over graphene-based photocatalysts.
查看更多>>摘要：Optimized electronic configuration is of critical importance for developing active multimetallic electrocatalysts for oxygen evolution reaction (OER) but remains a challenge. Herein, we report a defect-rich samarium ortho-ferrite interfaced with samarium-doped nickel ferrite (SFO/Sm-NFO) as an efficient OER electrocatalyst. By multiple in situ ion-exchanges and calcination processes, the inverse degree and defects of SFO/Sm-NFO are effectively regulated to modulate the electronic structure at the interface. Our experimental and theoretical studies show that the Sm doping in NFO inverse spinels facilitates the rearrangement of Ni atoms to the octa-hedral sites that are the active site for OER. This enables highly enhanced OER activity as manifested by a low overpotential of 228 mV at 10 mA cm(-2) (Tafel slope = 38.6 mV dec(-1)) with excellent stability at 500 and 1000 mA cm(-2) for 100 h. This work provides useful insights into the rational designing of multimetallic nanohybrids for active and practical electrocatalysts.
查看更多>>摘要：Visible-light catalytic H-2 production is being actively studied as a promising route to replace fossil fuel and improve the environment. Anion doped TiO2 is a kind of modified semiconductor with great research potential. However, the depth of anion substitution is difficult to control and hence its impact on photo-generated carriers is controversial. In addition, the effect of interfacial anion doping on the deposition behavior of co-catalyst is not clear. Herein, only bulk B-doped TiO2 (OB/TiO2) and surface to bulk B-doped TiO2 (STB/TiO2) were prepared successfully. They exhibited excellent visible-light catalytic H-2 production rate, which were 73 times (488.4 mu mol/g/h) and 26 times (171.6 mu mol/g/h) higher than that of the Blank TiO2 (6.7 mu mol/g/h), respectively. By multiple characterizations, directional deposition of Pt induced by electron-deficient structure was observed and photo-generated hole trapping site (Ti-4+O-2-Ti-4+O-4(.-)) was identified in subsurface of TiO2. Surface B would accelerate the recombination of photo-generated carriers, and thus render the photocatalytic performance of OB/TiO2 superior to STB/TiO2. This work provides valuable insights for rationally designing anion doped TiO2 and maximizing the photocatalytic efficiency via structural optimizations.
查看更多>>摘要：The unique physicochemical properties presented in the interface of composite oxides would result in some new features. Herein, MOx/TiO2 (M = Co, Mn, Ce, Cu, Fe) composites were constructed and successfully applied in the full spectrum light-assisted photothermal catalytic degradation of toluene. A unique p-n heterojunction with interface defects caused by lattice mismatch was constructed between TiO2 and Co3O4. The relationship between interface properties, band structure and photothermal catalytic performance based on experimental results and theoretical calculations had been studied comprehensively. The interfacial oxygen vacancy could improve ox-ygen mobility and provide more surface reactive oxygen species. The built-in electric field generated by electron transfer at the interface effectively promoted electron-hole pairs migration in the opposite direction. More active radicals and holes were provided to enhance the photothermal performance of CoTi catalyst. Furthermore, the possible reaction pathway of toluene and the photothermal synergy mechanism was proposed.
查看更多>>摘要：Snowflake-like Cu2S/MoS2 heterostructures with varied compositions were constructed via a two-step hydro thermal method. The 45-Cu2S/MoS2 with 45 wt% Cu2S was found as the optimum catalyst, which displayed photothermal enhanced hydrogen evolution reaction (HER) performance under near infrared (NIR) irradiation. After electrochemical deposition of a tiny amount of Pt (45-Cu2S/MoS2/Pt-100s), Schottky barrier was formed between Pt nanoparticles and MoS2 nanosheets. Using 45-Cu2S/MoS2/Pt-100s as an electrocatalyst, low over potential of 78 mV (@10 mV cm(-2)) and Tafel slope of 48 mV dec(-1) were achieved with the assistance of NIR irradiation. The photoelectrochemical (PEC) hydrogen production performance of 45-Cu2S/MoS2/Pt-100s was also investigated. The optimal conversion efficiency of 45-Cu2S/MoS2/Pt-100s could reach 0.78% at 0.57 V (vs. reversible hydrogen electrode (RHE)). The control of the internal geometric and electronic structure of the catalysts and the aid of photothermal effect in this work provide new ideas for designing high-efficiency hydrogen evolution catalysts.
查看更多>>摘要：As one of appealing storage patterns of solar energy, the efficient photocatalytic hydrogen evolution from water splitting has great potentiality in sustainable development for renewable energy, but it still suffers the low conversion level due to sluggish spatial behavior of photocarriers. Herein, on the basis of phase engineering theory, a novel conceptual design of energy band-gradient distribution is presented to consolidate the spatial transportation continuity of photocarriers, which is realized in the phase junction of CdS for the first time. Further being integrated with black phosphorus (BP) nanodots, the utilization of incident photons is extended to cover broad solar light-responsive window, and the p-n junctions with powerful internal electric fields resemble many accelerators distributed on the energy band-gradient pathway, thus furnishing sufficient internal dynamical transfer force for separation and migration of photocarriers with prolonged lifetime. The peculiar compound photocatalyst exhibits an excellent hydrogen evolution activity of 163.65 mu mol.h(-1).g(-1 ) and 5.72 mmol.h(-1).g(-1), as well as high apparent quantum yields (0.73 % and 25.7 % at 420 nm) under different conditions (with or without sacrificial agents). This study proposes a new exploitation strategy for the manipulation of energy band-gradient configuration in designing superior photocatalytic systems with available solar conversion efficiency.
查看更多>>摘要：The ability of hematite (alpha-Fe2O3) for photoelectrochemical water oxidation is limited by its poor conductivity. The construction of core-shell photoanode with a cocatalyst overlayer of metal-organic frameworks (MOFs) has been recognized as an effective method to enhance activity and stability. However, most MOFs cocatalysts are insulators, charge conductivity of MOFs and surface state of alpha-Fe2O3 synchronously modulation are needed for efficient carrier migration. In this study, a conductive MOFs (cMOFs) overlayer based on 2,5-dihydroxybenzoquinone was conformally coated on Ti:Fe2O3 using caffeic acid as coordination agent. The catechol groups in caffeic acid not only bridges Ti:Fe(2)O(3 )with cMOFs, but also regulates the surface state of Ti:Fe2O3. Coordination of catechol with Ti:Fe2O3 results in shortening of Fe-O bond and generation of surface state of high energy, thereby increasing its capacity for holes storage. The synthesized Ti:Fe2O3@CoFe-cMOFs exhibits outstanding photo current density of 3.3 mA cm(-2) with high stability.
查看更多>>摘要：The development of highly active non-precious metal-based electrocatalysts to accelerate the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is an essential issue for practical application of metal-air batteries. Herein, hydrothermal and annealing processes are employed to prepare FeCo alloy nanoparticles in Ndoped carbon shells on a defect-rich carbon support (FeCoNC/D). The introduction of defect-rich carbon support combined with the strong coupling of distributed FeCo alloy and N-doped carbon shell efficiently enhances the electrocatalytic activity. The FeCoNC/D exhibits superior bifunctional electrocatalytic activity with a half-wave potential of 892 mV (vs. RHE) for the ORR and an overpotential of 362 mV to drive a current density of 10 mA cm-2 for the OER. Moreover, Zn-air secondary battery prepared with FeCoNC/D displays a higher specific capacity of 725 mA h gZn -1, a power density of 157 mW cm-2 at 245 mA cm-2, and long-term cycling stability compared to state-of-the-art Pt/C-RuO2.
查看更多>>摘要：Cathode materials with high catalytic activity for H2O2 production and Fe2+ regeneration are essential to an efficient electro-Fenton process. Herein, we demonstrate a facile self-sacrificial template route to synthesize heteroatom-doped porous biochar. Owing to the created hierarchical porous structure and active defects, more generated oxygen functional groups (COOH/C-O-C) and modulated nitrogen dopants, the biochar cathode exhibits enhanced electrocatalytic activity. It achieves a high H2O2 selectivity (92%), facilitated Fe2+ regeneration, and an efficient H2O2 activation rate (82%). Various organic contaminants, including endocrine-disrupting chemicals, phenols, and antibiotics, can be effectively degraded with removal efficiencies of 98-100% within 15 min. The mineralization efficiencies achieve 83-100% with energy consumption of 0.87-1.07 kWh m- 3. Moreover, the electro-Fenton system exhibits good stability and versatile applicability for organic pollutants remediation in different surface water matrices. This study offers valuable insights into the preparation of costeffective cathode materials for an efficient electro-Fenton process.
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Elsevier