Search

Micropatterns of hierarchically ordered carbon tubes (i.e., ordered carbon microtubes composed of aligned carbon nanotubes) were grown on a film-like iron/silica substrate consisting of ring-like catalyst patterns. The substrates were prepared by a combined technique, in which the sol–gel method was used to prepare catalyst film and transmission electron microscope grids were used as a shadow mask. In comparison with other techniques that involve sophisticated lithography, this approach represents a simple and low-cost way to the micropatterning of aligned carbon nanotubes. [Copyright &y& Elsevier]

Abstract Development of heterostructured photocatalysts that promotes charge separation of semiconductor materials is crucial towards efficient photocatalytic hydrogen evolution. Here nanodiamond (ND)@graphitic carbon nitride (g-C 3 N 4) nanosheet heterostructures were synthesized via a facile one-step pyrolysis approach. The ND@g-C 3 N 4 heterostructures exhibit enhanced photocatalytic activity for hydrogen evolution from water splitting as compared with pristine g-C 3 N 4. The optimal heterostructures with 10 wt% ND loading content show the best performance in photocatalytic H 2 evolution under visible light irradiation, which is more than 5.6 times higher than that of the pristine g-C 3 N 4. The increased light-trapping induced by the scattering of the NDs promotes more localized charge carriers generation, which is clarified by the combined experimental results and finite difference time domain simulations. Meanwhile, the effective charge separation at the ND@g-C 3 N 4 interface due to the energy level matching can synergistically induce the enhanced photocatalytic activity of g-C 3 N 4. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

The well-designed FeCo-MOF/Fe 2 O 3 compound photoanode displays favorable PEC performances, which can be attributed to the coating of multifunctional FeCo MOF nanolayer that passivate the surface states, construct the p-n heterojunction and improve the water oxidation kinetics, all of these enable the substantially promoted charge separation and transport. [Display omitted] • Ultrathin FeCo MOF nanolayers coated on Fe 2 O 3 photoanode are in-situ formed. • Multifunctional roles of FeCo MOF on Fe 2 O 3 is disclosed. • This design endows photoanode with boosted charge separation/injection efficiency. • The catalytic mechanism for PEC water oxidation is unravelled. Owing to the high theoretical photocurrent density, the hematite (α -Fe 2 O 3) based photoanode has been intensively concerned in photoelectrochemical (PEC) water splitting, but its serious charge recombination and sluggish water oxidation kinetics are still the stumbling blocks. This work reports a high-performance Fe 2 O 3 -based photoanode achieved by coating multifunctional FeCo-bimetal organic framework (MOF) nanolayers (NLs) on Fe 2 O 3 nanoarrays via an in-situ solvothermal process. The FeCo MOF NLs introduced not only effectively passivate the surface states of Fe 2 O 3 photoanode and boost the water oxidation kinetics serving as the cocatalyst, but also construct p-n heterojunctions with Fe 2 O 3 to accelerate the directional migration and separation of photogenerated charge carriers. Expectedly, the as-obtained FeCo-MOF/Fe 2 O 3 photoanode exhibits an apparent negative shift of onset potential, an excellent long-term PEC stability, and highly improved photocurrent density. This finding provides a novel and effective strategy to introduce advanced multifunctional surface coating for enhancing the PEC performance of photoelectrodes. [ABSTRACT FROM AUTHOR]

The well-designed MoO 3- x /Fe 2 O 3- x photoanode exhibits superior PEC water oxidation performance due to the efficient charge separation and transport derived from the introduced MoO 3 surface passivation layer and oxygen vacancy. • Establishing passivation effect of MoO 3 on Fe 2 O 3 photoanode. • Collaboration of passivation layer and oxygen vacancy on Fe 2 O 3 was designed. • The boosted charge separation and transport are achieved on modified photoanode. • Exhibiting superior water oxidation performance on MoO 3- x /Fe 2 O 3- x photoanode. To seek effective strategies that improve the photoelectrochemical water oxidation performance of hematite (α -Fe 2 O 3) photoanodes is still challenging owning to their abundant surface states and low charge transfer efficiency. Herein, a facile impregnation method with an annealing process was developed to synthesize MoO 3 modified Fe 2 O 3 photoanodes using the MoO 3 layer as an effective passivation component to decrease surface states and thus to improve the charge separation and transfer process at the electrode/electrolyte interfaces. The oxygen vacancies were subsequently introduced to steer the electrical conductivity, and further to boost the charge separation and transfer. The optimized MoO 3- x /Fe 2 O 3- x photoanode displays a photocurrent density of 2.6 mA cm–2 at 1.23 V versus the reversible hydrogen electrode under AM 1.5 G irradiation, 2.2 times that of the Fe 2 O 3 (1.2 mA cm–2). The synergetic integration of passivation layer and oxygen vacancies on photoelectrodes heralds an efficient paradigm for solar energy conversion. [ABSTRACT FROM AUTHOR]

The decoration of In 2 O 3 nanolayers on hematite nanoarray photoanode are successfully synthesized to reduce the surface recombination of charge carriers and prolong their lifetimes. The coupling effects of surface passivation and interface electric field enhancement for In 2 O 3 endows the Fe 2 O 3 photoanode with significantly enhanced PEC performance for water oxidation. • In 2 O 3 effectively passivated surface states and enhanced interface electric field of Fe 2 O 3 photoanode. • High charge separation and transportation are achieved both in bulk and surface. • The catalytic mechanism of In 2 O 3 /Fe 2 O 3 nanoarray photoanode is fully excavated. • The high IPCE of 80 % is recorded at 400 nm. Hematite (α -Fe 2 O 3) based nanomaterials are considered as the most promising photoelectrodes for solar water splitting. However, some inherent shortcomings like high density of surface states is still the critically challengeable issue. This paper reports the integration of In 2 O 3 nanolayers (NLs) on the surface of worm-like Fe 2 O 3 films to significantly improve the photoelectrochemical (PEC) water oxidation activity. The In 2 O 3 NLs on the modified α -Fe 2 O 3 photoelectrodes exhibit dual positive effects on PEC performance: i) acting as the passivation material to decrease surface electron-hole recombination losses; ii) constructing heterojunctions with Fe 2 O 3 to facilitate efficient separation of surface charges and spatial transfer with extended lifetimes. The resulting treated Fe 2 O 3 photoanode yields a current density of 3.4 mA cm―2 at 1.23 V vs. reversible hydrogen electrode and high incident photon-to-current efficiency of 80 % at 400 nm. These results may bring inspiration to introduce multifunctional modifiers on photoelectrodes that offer practically high-performance PEC applications. [ABSTRACT FROM AUTHOR]