Over the last 2 years, it has been observed that metal phosphides have emerged as efficient electrocatalysts for both hydrogen and oxygen evolution reactions (HER and OER). However, while the HER has been immensely studied, the OER is limited. The chemistry in the OER is more complicated and involves irreversible surface oxidations of these materials and transforms them to their corresponding oxide/oxyhydroxide. Interestingly, these in situ changes have been widely observed generating more active catalysts with superior performance. Phosphides of Fe, Co, and Ni with different compositions have been proved as efficient catalysts for water oxidation. Considering their importance, structures, compositions, surface modifications, and also in situ transformation during electrolysis, this Perspective provides state-of-the-art views of their current developments and future prospects.

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We show that a thermally isolated system driven across a quantum phase transition by a noisy control field exhibits anti-Kibble-Zurek behavior, whereby slower driving results in higher excitations. We characterize the density of excitations as a function of the ramping rate and the noise strength. The optimal driving time to minimize excitations is shown to scale as a universal power law of the noise strength. Our findings reveal the limitations of adiabatic protocols such as quantum annealing and demonstrate the universality of the optimal ramping rate.Understanding adiabatic dynamics and its breakdown in many-body systems is fundamental to the progress of quantum technologies [1]. Adiabatic evolution is the cornerstone of the quantum annealing scheme for state preparation and quantum computation [2, 3]. The adiabatic theorem states that the dynamics of a physical system is free from diabatic transitions under slow driving [4]. The suppression of excitations becomes challenging in the absence of an energy gap, e.g., when crossing a quantum critical point (QCP) [5][6][7]. The density of excitation follows a universal power aw as a function of the rate of change of the control field driving the system through the QCP [8-11] and can be reduced by resorting to slow ramps. This universal scaling is the key prediction of the Kibble-Zurek mechanism (KZM), initially developed for classical continuous phase transitions [12,13].While its experimental verification still calls for further studies [7], KZM is believed to be broadly applicable. Yet, a conflicting observation has been reported in the study of mutiferroic systems: approaching the adiabatic limit, slower ramps generate more excitations [14]. This counterintuitive phenomenon was termed anti-Kibble-Zurek (anti-KZ) dynamics. While tests of KZM in the quantum regime are scarce, the data in one of them hint at a possible anti-KZ behavior [15]. Here we show that in a thermally isolated quantum system, the presence of noisy fluctuations in the control field naturally provides an explanation for anti-KZ behavior.We start by considering a linear passage through the QCP. A control field g is turned on from zero value to unity as in standard quantum annealing schemes, crossing a QCP at g c = 1 2 . When the transition is crossed at a rate 1/τ fixed by the ramp duration τ, KZM predicts universal power-law for the density of excitations n 0 ∝ τ −β , with β = dν/(1 + zν), where ν and z are the correlation length and dynamic critical exponents, and d is the dimensionality of the system. The subindex in n 0 is introduced to denote noise-free driving. The density of excitations monotonically decreases with τ and vanishes in the limit of τ → ∞.The control over the system, however, is never perfect. In particular, the modulation in time of the control field might be subject to noise [16][17][18][19][20]. In our study, we consider a thermally isolated system with no coupling to a thermal environment or heat bath, discussed in [21][22][23][24][25][26][27][28]. While the dynamics is ...

In nanoscale, with size variation, Au shows different optical behaviors. For the small size clusters (sub-5 nm), it behaves more like semiconductors having sp and d band electronic energy levels splitting and also do not show the characteristic plasmon. However, for larger size particles (>5 nm), it shows the plasmonic absorption. Considering these two structures of Au 0 , we report here their coupling with a low bandgap semiconductor SnS and study the difference in their formation chemistry and materials' properties. Following a common synthetic approach in which a smaller size SnS cube and tetrahedron shapes result in Au cluster decorated Au-SnS heterostructures, larger size SnS cubes form coupled Au-SnS nanostructures. Contrastingly, the nonplasmonic Au 0 cluster-SnS hinders the photocatalytic activity, whereas the plasmonic coupled Au-SnS enhances the catalytic activity toward reduction of organic dye methylene blue. However, both types of heterostructures show enhanced photocurrent as well as photoresponse activities. Details of the chemistry of formation, epitaxy at the junction, and change in the materials' properties are studied and reported here in this article.

We study the role of long-range interactions (more precisely, the long-range superconducting gap term) on the non-equilibrium dynamics considering a long-range p-wave superconducting chain in which superconducting term decays with distance between two sites in a power-law fashion characterised by an exponent α. We show that the Kibble-Zurek scaling exponent, dictating the power-law decay of the defect density in the final state reached following a slow (in comparison to the time-scale associated with the minimum gap in the spectrum of the Hamiltonian) quenching of the chemical potential (µ) across a quantum critical point, depends non-trivially on the exponent α as long as α < 2; on the other hand, for α > 2, one finds that the exponent saturates to the corresponding well-know value of 1/2 expected for the short-range model. Furthermore, studying the dynamical quantum phase transitions manifested in the non-analyticities in the rate function of the return possibility (I(t)) in subsequent temporal evolution following a sudden change in µ, we show the existence of a new region; in this region, we find three instants of cusp singularities in I(t) associated with a single sector of Fisher zeros. Notably, the width of this region shrinks as α increases and vanishes in the limit α → 2 indicating that this special region is an artefact of long-range nature of the Hamiltonian. arXiv:1705.03770v2 [cond-mat.stat-mech]