Organic photoactive materials are promising candidates for the generation of solar fuels in terms of efficiency and cost. However, their low stability in aqueous media constitutes a serious problem for technological deployment. Here we present organic photocathodes for the generation of hydrogen in aqueous media with outstanding stability. The device design relies on the use of water-resistant selective contacts, which protect a P3HT:PCBM photoactive layer. An insoluble cross-linked PEDOT:PSS hole-selective layer avoids delamination of the film, and an electron-selective TiO x layer in contact with the aqueous solution electrically communicates the organic layer with the hydrogen-evolving catalyst (Pt). We developed a novel method for the synthesis of the TiO x layer compatible with low-temperature conditions. Tuning the thickness of the TiO x /Pt layer leads to a trade-off between the achievable photocurrent (∼1 mAcm −2) and the stability of the photocathode (stable hydrogen generation of 1.5 μmol h −1 cm −2 for >3 h).

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A model predictive control (MPC) scheme integrated with a recently developed fault detection, isolation, and estimation (FDIE) system applied on a pulp mill (PM) process is discussed. This work belongs to a series whose objective is to achieve improvements on the fault tolerance characteristics for conventional and advanced control schemes. In two previous works, different decentralized control structures were integrated with the same FDIE system. It was tested for large chemical plants, such as PM and wastewater treatment plant (WWTP) processes. Each one offered different dynamics and fault scenarios, because of the specific impact produced by the abnormal events considered. For doing rigorous comparisons, the PM process is the same as that studied in one of the previous works. Although the FDIE system presents the same general structure, it must be redesigned, because of the inherent fault-tolerant characteristics of the classical MPC. In this context, it is more difficult to determine the patterns associated with each fault. A complete set of simulation results, evaluated by the same indexes used in the previous work, together with a cost analysis about the process operational profits, is included. The comparisons are done with and without the FDIE system, alternative control solutions providing from the decentralized and MPC structures are evaluated. The case where the link with the FDIE system is done is indicated as fault-tolerant MPC (FTMPC). As new results, a rigorous quantitative analysis to answer the question about which is the real improvement that can be introduced by the FTMPC is made, accounting for very complex scenarios.