Probing the Reactivity of Functionalized Surfaces by Porphyrin Metalation

Nowakowski, Jan; Nowakowska, Sylwia; Srivastava, Gitika; Baljozović, Miloš; Girovský, Ján; Ballav, Nirmalya; Jung, Thomas A.

doi:10.1002/slct.201600215

Cited by 3 publications

(2 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The deconvoluted Ni2p peak at binding energies of 852.5 eV corresponds to Ni metal shown in Fig. 4E which agrees well with those reported for Ni metal 53 .…”

Section: Resultssupporting

confidence: 88%

Ultrathin Assembles of Porous Array for Enhanced H2 Evolution

Islam¹,

Teo

Awual

et al. 2020

Sci Rep

View full text Add to dashboard Cite

Since the complexity of photocatalyst synthesis process and high cost of noble cocatalyst leftovers a major hurdle to producing hydrogen (H 2 ) from water, a noble metal-free Ni-Si/MgO photocatalyst was realized for the first time to generate H 2 effectively under illumination with visible light. The catalyst was produced by means of simple one-pot solid reaction using self-designed metal reactor. The physiochemical properties of photocatalyst were identified by XRD, FESEM, HRTEM, EDX, UVvisible, XPS, GC and PL. The photocatalytic activities of Ni-Si/MgO photocatalyst at different nickel concentrations were evaluated without adjusting pH, applied voltage, sacrificial agent or electron donor. The ultrathin-nanosheet with hierarchically porous structure of catalyst was found to exhibit higher photocatalytic H 2 production than hexagonal nanorods structured catalyst, which suggests that the randomly branched nanosheets are more active surface to increase the light-harvesting efficiency due to its short electron diffusion path. The catalyst exhibited remarkable performance reaching up to 714 µmolh −1 which is higher among the predominant semiconductor catalyst. The results demonstrated that the photocatalytic reaction irradiated under visible light illumination through the production of hydrogen and hydroxyl radicals on metals. The outcome indicates an important step forward one-pot facile approach to prepare noble ultrathin photocatalyst for hydrogen production from water.Why do we need to promote hydrogen energy? The scientist lays out about four main reasons-energy-saving, minimal ecological impacts, energy security and industrial competitiveness. Industrially, fossil-fuel based hydrogen production process emits greenhouse gas to the environment 1 . The use of solar energy to produce hydrogen from water could accelerate the development of high-impact breakthrough clean energy technologies. By developing an optimal photocatalyst, scientists are searching for the ways of improving clean energy (H 2 ) production from water without producing greenhouse gases or having many adverse effects on the atmosphere.A variety of titanium dioxide (TiO 2 ) phases and nanostructures have been studied extensively for photocatalytic hydrogen production because of its earth-abundance, non-toxicity as well as thermal and chemical stability 1,2 . However, photoirradiated electron recombination and wide band gap of bare TiO 2 remain challenge on efficient hydrogen production. Much work has been directed towards the adaptation of noble Pd, Au metals on the TiO 2 metals 3-5 or through the use of sacrificial reagents 6 . Noble co-catalyst could serve as electron sinks to isolate the photogenerated electron-holes 3 . Moreover, noble metals assist to boost the reaction process by lowering over-potential for proton deduction 4 . Unfortunately, the state-of-the-art co-catalysts are still noble metals (e.g. Pt, Au, Pd) or their oxides that are rare and expensive. As a consequence, the discovery of robust, low-cost and earth-abundant co-catalyst...

show abstract

“…The deconvoluted Ni2p peak at binding energies of 852.5 eV corresponds to Ni metal shown in Fig. 4E which agrees well with those reported for Ni metal 53 .…”

Section: Resultssupporting

confidence: 88%

Ultrathin Assembles of Porous Array for Enhanced H2 Evolution

Islam¹,

Teo

Awual

et al. 2020

Sci Rep

View full text Add to dashboard Cite

show abstract

“…A monolayer of chlorine atoms on Cu(100) exhibits a surface band gap E g of about 7 eV (see inset of Fig. 1a) as well as a shift in the substrate's work function by 1.25 eV [20], suggesting a significant charge transfer between the substrate and chlorine atoms and formation of the interface dipole moment [21]. Theoretical calculations predict a charge of 0.5 electron accumulated on chlorine atoms and depletion of the density of states (DOS) at the top-most layer of the copper substrate [22].…”

mentioning

confidence: 99%

Emergence of quasiparticle Bloch states in artificial crystals crafted atom-by-atom

et al. 2017

Self Cite

View full text Add to dashboard Cite

The interaction of electrons with a periodic potential of atoms in crystalline solids gives rise to band structure. The band structure of existing materials can be measured by photoemission spectroscopy and accurately understood in terms of the tight-binding model, however not many experimental approaches exist that allow to tailor artificial crystal lattices using a bottom-up approach. The ability to engineer and study atomically crafted designer materials by scanning tunnelling microscopy and spectroscopy (STM/STS) helps to understand the emergence of material properties. Here, we use atom manipulation of individual vacancies in a chlorine monolayer on Cu(100) to construct one-and two-dimensional structures of various densities and sizes. Local STS measurements reveal the emergence of quasiparticle bands, evidenced by standing Bloch waves, with tuneable dispersion. The experimental data are understood in terms of a tightbinding model combined with an additional broadening term that allows an estimation of the coupling to the underlying substrate. Atom manipulation by means of STM is a viable way of constructing atomically precise artificial structures [1]. Among others, the technique can be used to engineer atomic scale logic devices [2,3], low dimensional magnetic systems [4][5][6] or atomic data storages [7][8][9]. As our abilities to manipulate atoms on a large scale are improving, the formation of atomically designed artificial crystals becomes of particular interest driven by a demand for new materials where the properties are defined by emerging quasiparticle states [10]. Common approaches to build low-dimensional artificial materials by STM include confinement of electronic surface states through precise assembly of individual atoms and/or molecules [11][12][13][14], self-assembly of molecular networks [15,16] and manipulation of dangling bonds [17] or surface vacancies [18]. The recent development of large-scale fully automated placement of atomic vacancies on a chlorinated copper crystal surface [9] provides an excellent platform to explore various lattice compositions. These vacancies were found to host a localized vacancy state in the surface band gap, similar to dopants in semiconductors, allowing their combined electronic states to be modelled by means of tight-binding approximation [19]. 1SciPost Phys. 2, 020 (2017) Here, we present a study of artificial one-and two-dimensional structures built from Cl vacancies in an otherwise perfect monolayer square lattice formed by chlorine atoms on a Cu(100) surface. Using local electron tunnelling spectroscopy, we demonstrate that we are able to reach system scales where the spectral properties no longer depend on size and which we therefore consider to be in the limit of infinite lattice size. For structures with a sufficiently large vacancy density, we observe quasiparticle Bloch waves that can be simulated by using a tight-binding model. Similar wave patterns were reported previously in assembled chains of Au atoms [14], which were best descr...

show abstract