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.

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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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