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A gas‐phase approach to form Zn coordination sites on metal–organic frameworks (MOFs) by vapor‐phase infiltration (VPI) was developed. Compared to Zn sites synthesized by the solution‐phase method, VPI samples revealed approximately 2.8 % internal strain. Faradaic efficiency towards conversion of CO₂to CO was enhanced by up to a factor of four, and the initial potential was positively shifted by 200–300 mV. Using element‐specific X‐ray absorption spectroscopy, the local coordination environment of the Zn center was determined to have square‐pyramidal geometry with four Zn−N bonds in the equatorial plane and one Zn‐OH₂bond in the axial plane. The fine‐tuned internal strain was further supported by monitoring changes in XRD and UV/Visible absorption spectra across a range of infiltration cycles. The ability to use internal strain to increase catalytic activity of MOFs suggests that applying this strategy will enhance intrinsic catalytic capabilities of a variety of porous materials.

 

Engineering catalytic sites at the atomic level provide an opportunity to understand the catalyst’s active sites, which is vital to the development of improved catalysts. Herein, we show a reliable and tunable polyoxometalate (POM) template-based synthetic strategy to atomically engineer metal doping sites onto metallic 1T-MoS2, using Anderson-type POMs (XMo6, X = FeIII, CoIII, or NiII) as precursors. Benefiting from the synergistic effect of doping metals into 1T-MoS2 and the possible tuning effect of the Ni-O-Mo bond, the optimized Ni and O incorporated 1T-MoS2 (NiO@1T-MoS2) catalyst excels in the hydrogen evolution reaction (HER). With a positive onset potential of ~ 0 V and a low overpotential of -46 mV in 1.0 M KOH, its results are comparable to 20% Pt/C. First-principles calculations reveal co-doping Ni and O into 1T-MoS2 assists the processes of both water dissociation and hydrogen generation from their intermediate states. This research will expand on the ability to improve the activities of various catalysts by precisely engineering atomic activation sites to achieve significant electronic modulations and improve atomic utilization efficiencies. 

Photoelectrode degradation under harsh solution conditions continues to be a major hurdle for long-term operation and large-scale implementation of solar fuel conversion. In this study, a dual-layer TiO2 protection strategy is presented to improve the interfacial durability between nanoporous black silicon and photocatalysts. Nanoporous silicon photocathodes decorated with catalysts are passivated twice, providing an intermediate TiO2 layer between the substrate and catalyst and an additional TiO2 layer on top of the catalysts. Atomic layer deposition of TiO2 ensures uniform coverage of both the nanoporous silicon substrate and the catalysts. After 24 h of electrolysis at pH = 0.3, unprotected photocathodes layered with platinum and molybdenum sulfide retain only 30% and 20% of their photocurrent, respectively. At the same pH, photocathodes layered with TiO2 experience an increase in photocurrent retention: 85% for platinum-coated photocathodes and 91% for molybdenum sulfide–coated photocathodes. Under alkaline conditions, unprotected photocathodes experience a 95% loss in photocurrent within the first 4 h of electrolysis. In contrast, TiO2-protected photocathodes maintain 70% of their photocurrent during 12 h of electrolysis. This approach is quite general and may be employed as a protection strategy for a variety of photoabsorber–catalyst interfaces under both acidic and basic electrolyte conditions 

Unbiased photoelectrochemical hydrogen production with high efficiency and durability is highly desired for solar energy storage. Here, we report a microbial photoelectrochemical (MPEC) system that demonstrated superior performance when equipped with bioanodes and black silicon photocathode with a unique ‘‘Swiss-cheese’’ interface. The MPEC utilizes the chemical energy embedded in wastewater organics to boost solar H2 production, which overcomes barriers on anode H2O oxidation. Without any bias, the MPEC generates a record photocurrent (up to 23 mA cm2) and retains prolonged stability for over 90 hours with high Faradaic efficiency (96–99%). The calculated turnover number for MoSx catalyst during a 90 h period is 495 471 with an average frequency of 1.53 s1 . The system replaced pure water on the anode with actual wastewater and achieved waste organic removal up to 16 kg COD m2 photocathode per day. Cost credits from concurrent wastewater treatment and low-cost design make photoelectrochemical H2 production practical for the first time 

An efficient, durable, and low‐cost hydrogen evolution reaction (HER) catalyst is an essential requirement for practical hydrogen production. Herein, an effective approach to facilitate the HER kinetics of molybdenum carbide (Mo2C) electrocatalysts is presented by tuning its electronic structure through atomic engineering of nitrogen implantation. Starting from the organoimido‐derivatized polyoxometalate nanoclusters with inherent Mo-N bonds, the formation of N‐implanted Mo2C (N@Mo2C) nanocrystals with perfectly adjustable amounts of N atoms is demonstrated. The optimized N@Mo2C electrocatalyst exhibits remarkable HER performance and good stability over 20 h in both acid and basic electrolytes. Further density functional theory calculations show that engineering suitable nitrogen atoms into Mo2C can regulate its electronic structure well and decrease Mo-H strength, leading to a great enhancement. 

Current artificial photosynthesis (APS) systems are promising for the storage of solar energy via transportable and storable fuels, but the anodic half-reaction of water oxidation is an energy intensive process which in many cases poorly couples with the cathodic half-reaction. Here we demonstrate a self-sustaining microbial photoelectrosynthesis (MPES) system that pairs microbial electrochemical oxidation with photoelectrochemical water reduction for energy efficient H2 generation. MPES reduces the overall energy requirements thereby greatly expanding the range of semiconductors that can be utilized in APS. Due to the recovery of chemical energy from waste organics by the mild microbial process and utilization of cost-effective and stable catalyst/electrode materials, our MPES system produced a stable current of 0.4 mA/cm2 for 24 h without any external bias and ∼10 mA/cm2 with a modest bias under one sun illumination. This system also showed other merits, such as creating benefits of wastewater treatment and facile preparation and scalability.