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Abstract Hydrogen bonding principles are at the core of supramolecular design. This overview features a discussion relating molecular structure to hydrogen bond strengths, highlighting the following electronic effects on hydrogen bonding: electronegativity, steric effects, electrostatic effects, π‐conjugation, and network cooperativity. Historical developments, along with experimental and computational efforts, leading up to the birth of the hydrogen bond concept, the discovery of nonclassical hydrogen bonds (CH…O, OH…π, dihydrogen bonding), and the proposal of hydrogen bond design principles (e.g., secondary electrostatic interactions, resonance‐assisted hydrogen bonding, and aromaticity effects) are outlined. Applications of hydrogen bond design principles are presented. This article is categorized under: Structure and Mechanism > Molecular Structures Structure and Mechanism > Reaction Mechanisms and Catalysis
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High throughput methodology for investigating green hydrogen generating processes using colorimetric detection films and machine vision
In this work, colorimetric hydrogen detection films are presented as an open source, high-throughput approach for the investigation of photo-driven hydrogen evolution reactions.
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- Award ID(s):
- 2102460
- PAR ID:
- 10540753
- Publisher / Repository:
- Royal Society of Chemistry
- Date Published:
- Journal Name:
- Digital Discovery
- Volume:
- 3
- Issue:
- 7
- ISSN:
- 2635-098X
- Page Range / eLocation ID:
- 1430 to 1440
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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IntroductionDeveloping sustainable hydrogen production is critical for advancing renewable energy and reducing reliance on fossil fuels. Cyanobacteria, which harness solar energy through photosynthesis, provide a promising biological platform for hydrogen generation. However, improving hydrogen yields requires strategic metabolic and genetic modifications to optimize energy flow and overcome photosynthetic limitations. MethodsFour cyanobacterial species were evaluated for their hydrogen production capacities under varying experimental conditions. Photosynthesis was partially inhibited using distinct chemical inhibitors, including 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). Exogenous glycerol was introduced as a supplementary carbon source. Hydrogen production was monitored over time, and rates were normalized to chlorophyll a content. Genomic analysis of transporter proteins was conducted to identify potential genetic loci for further enhancement of hydrogen output. ResultsNitrogen-fixingDolichospermumsp. exhibited significantly higher hydrogen production compared to the other tested species. Supplementation with glycerol notably increased both the rate and duration of hydrogen evolution, far exceeding previously established benchmarks. The maximum hydrogen production rate forDolichospermumsp. reached 132.3 μmol H₂/mg Chl a/h—representing a 30-fold enhancement over the rates observed with DCMU. Genomic screening revealed key transporter proteins with putative roles in carbon uptake and hydrogen metabolism. DiscussionThese findings underscore the potential of cyanobacteria, particularlyDolichospermumsp., as robust platforms for sustainable hydrogen production. The substantial improvements in hydrogen yield highlight the importance of targeted metabolic engineering and carbon supplementation strategies. Future work focused on optimizing identified transporter proteins and refining genetic interventions could further enhance biohydrogen efficiency. By leveraging the inherent photosynthetic machinery of cyanobacteria, this platform offers a renewable hydrogen source with significant promise for global energy sustainability.more » « less
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Abstract With increasing global interest in molecular hydrogen to replace fossil fuels, more attention is being paid to potential leakages of hydrogen into the atmosphere and its environmental consequences. Hydrogen is not directly a greenhouse gas, but its chemical reactions change the abundances of the greenhouse gases methane, ozone, and stratospheric water vapor, as well as aerosols. Here, we use a model ensemble of five global atmospheric chemistry models to estimate the 100-year time-horizon Global Warming Potential (GWP100) of hydrogen. We estimate a hydrogen GWP100 of 11.6 ± 2.8 (one standard deviation). The uncertainty range covers soil uptake, photochemical production of hydrogen, the lifetimes of hydrogen and methane, and the hydroxyl radical feedback on methane and hydrogen. The hydrogen-induced changes are robust across the different models. It will be important to keep hydrogen leakages at a minimum to accomplish the benefits of switching to a hydrogen economy.more » « less
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Molecular hydrogen is produced by the fermentation of organic matter and consumed by organisms including hydrogenotrophic methanogens and sulfate reducers in anoxic marine sediment. The thermodynamic feasibility of these metabolisms depends strongly on organic matter reactivity and hydrogen concentrations; low organic matter reactivity and high hydrogen concentrations can inhibit fermentation so when organic matter is poor, fermenters might form syntrophies with methanogens and/or sulfate reducers who alleviate thermodynamic stress by keeping hydrogen concentrations low and tightly controlled. However, it is unclear how these metabolisms effect porewater hydrogen concentrations in natural marine sediments of different organic matter reactivities. MethodsWe measured aqueous concentrations of hydrogen, sulfate, methane, dissolved inorganic carbon, and sulfide with high-depth-resolution and 16S rRNA gene assays in sediment cores with low carbon reactivity in White Oak River (WOR) estuary, North Carolina, and those with high carbon reactivity in Cape Lookout Bight (CLB), North Carolina. We calculated the Gibbs energies of sulfate reduction and hydrogenotrophic methanogenesis. ResultsHydrogen concentrations were significantly higher in the sulfate reduction zone at CLB than WOR (mean: 0.716 vs. 0.437 nM H2) with highly contrasting hydrogen profiles. At WOR, hydrogen was extremely low and invariant (range: 0.41–0.52 nM H2) in the upper 15 cm. Deeper than 15 cm, hydrogen became more variable (range: 0.312–2.56 nM H2) and increased until methane production began at ~30 cm. At CLB, hydrogen was highly variable in the upper 15 cm (range: 0.08–2.18 nM H2). Ratios of inorganic carbon production to sulfate consumption show AOM drives sulfate reduction in WOR while degradation of organics drive sulfate reduction in CLB. DiscussionWe conclude more reactive organic matter increases hydrogen concentrations and their variability in anoxic marine sediments. In our AOM-dominated site, WOR, sulfate reducers have tight control on hydrogen via consortia with fermenters which leads to the lower observed variance due to interspecies hydrogen transfer. After sulfate depletion, hydrogen accumulates and becomes variable, supporting methanogenesis. This suggests that CLB’s more reactive organic matter allows fermentation to occur without tight metabolic coupling of fermenters to sulfate reducers, resulting in high and variable porewater hydrogen concentrations that prevent AOM from occurring through reverse hydrogenotrophic methanogenesis.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/d4dd00070f
