Quantum dot (QD) sensitized NiO photocathodes rely on efficient photoinduced hole injection into the NiO valence band. A system of a mesoporous NiO film co-sensitized with CdSe QDs and a molecular protonreduction catalyst was studied. While successful electron transfer from the excited QDs to the catalyst is observed, most of the photogenerated holes are instead quenched very rapidly (ps) by hole trapping at the surface thiols of the capping agent used as linker molecules. We confirmed our conclusion by first using a thiol free capping agent and second varying the thiol concentration on the QD's surface. The later resulted in faster hole trapping as the thiol concentration increased. We suggest that this hole trapping by the linker limits the H 2 yield for this photocathode in a device.
A simple quasi-static 2D model simulates the global stress relaxation of fractured rock mass due to local frictional slips • The fractures in the rock mass are stochastically assigned with varying frictional coefficients, representing the system heterogeneity • Global stress evolution of the stochastic case differs from its deterministic counterpart, extending the notion of frictional equilibrium Supporting Information:
Characterization of the in situ stresses is key to better understand the crustal deformation processes, such as fault slip (Scholz, 2019) and to tailor subsurface engineering designs (Cornet et al., 2007;Ma & Zoback, 2017). In general, the stress field within the intra-plate area is relatively uniform at regional scales (M. L. Zoback, 1992). However, the presence of ubiquitous discontinuities (e.g., veins, joints, fractures, and faults) at various scales in the crustal rock mass modifies the local stress fields (Pollard & Segall, 1987). In particular, faults, as complex geological structures, can exert significant influence on and interact with the local stress fields in an intricate manner.The state of stress is often not adequately understood in the vicinity of faults due to the complexity of the stress conditions and the availability of stress measurements therein (Stephansson & Zang, 2012). In general, stress fields at great depths are often inferred from earthquake focal mechanism inversions (Michael, 1984;Vavryčuk, 2014), while borehole/drillcore measurements are typically available for the stress estimation at shallow depths (
A simple quasi-static 2D model simulates the global stress relaxation of fractured rock mass due to local frictional slips • The fractures in the rock mass are stochastically assigned with varying frictional coefficients, representing the system heterogeneity • Global stress evolution of the stochastic case differs from its deterministic counterpart, extending the notion of frictional equilibrium Supporting Information:
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