10 research outputs found

    Women’s access to and control over land in the current land administration system in two rural kebeles in Ada’a Woreda of Oromia Region

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    The study is designed to explore the status of rural women in access to and control over land in the current land administration system in two rural Kebeles in East Shewa Zone Ada’a Woreda of Oromia region on smallholder farmers’ landholding registration. The Ormia National Regional State Rural Land Administration and Use Proclamation and its implementation procedure are examined from a gender perspective in terms of ensuring rural women’s land holding rights and control they have over land. Historical overview on the land question in Ethiopia revealed that tenure systems evolved through historical periods. Land remained under men’s control throughout history and men’s control over land was strengthened by the rural land reform carried out by the Derg. This tenure reform applied rural land distribution using households as unit for rural land allocation and women were disadvantaged as most rural households were headed by men. The Oromia rural land proclamation is not discriminatory on basis of sex. However, policy gaps are evident in addressing women specific issues such as issues of FHHs and women under polygamous marriages. Gaps also exist between policy and implementation. Customary laws and practices have serious impacts on women’s land rights at the level of implementation. The research applied both quantitative and qualitative methods in view of feminist research methodology to properly address issues from a gender perspective. Survey of 318 households was conducted administering questionnaires in the quantitative method. The qualitative method applied was interviews with relevant Woreda office and Kebele LACs, focus group discussions with rural women, case stories and observation. Triangulation method is applied in data collection, data presentation and in analysis of findings. Study findings reveal that women’s access rights to land is less equal than legally provided. This study evidences gaps between policy and implementation. Customary laws and traditional practices generally have impacts on land access rights of single/unmarried, divorced, widowed women and on access rights of women in polygamous marriages. Women’s control over land is not efficiently addressed by the regional rural land policy. This is a significant policy drawback as women’s equal rights on land could not be achieved without gaining control over land. The land administration system in general and the land registration process in particular has not considered women’s participation in community activities and decision-making. Women are not represented in LACs and Sub-Committees in both Kebeles. Study findings indicate absence of autonomous institution as gap in addressing women’s issues in the land administration system. This study also revealed loose linkages between the rural land policy and other regional legislations like the regional family law which provides women’s equal rights on land in marriage and on its abandonment. This study forwards recommendation to address gender gaps identified to ensure women’s equal access to and control over land in the study area. The Oromia rural land proclamation needs revision from a gender perspective to address women’s specific issues and the land administration system should consider women’s participation in the process, their contribution to the system as well as their equal benefits from policy outcomes

    Efficient Electrochemical and Photoelectrochemical H<sub>2</sub> Production from Water by a Cobalt Dithiolene One-Dimensional Metal–Organic Surface

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    Solar-driven hydrogen evolution from water has emerged as an important methodology for the storage of renewable energy in chemical bonds. Efficient and practical clean-energy devices for electrochemical or photoelectrochemical splitting of water require the immobilization of stable and active hydrogen-evolving catalysts onto electrode or photocathode materials, which remains a significant challenge. Here we show that cobalt­(II) reacts with benzene-1,2,4,5-tetrathiol in the presence of base to form a cobalt dithiolene polymer <b>1</b>. The generated polymer is immobilized onto glassy carbon electrodes (GCE) to generate a metal–organic surface (MOS <b>1</b>|GCE), which displays efficient H<sub>2</sub>-evolving activity and stability in acidic aqueous solutions. Moreover, the generated polymer is integrated with planar p-type Si to generate very efficient photocathode materials (MOS <b>1</b>|Si) for solar-driven hydrogen production from water. Photocurrents up to 3.8 mA/cm<sup>2</sup> at 0 V vs RHE were achieved under simulated 1 Sun illumination. MOS <b>1</b>|Si photocathodes operate at potentials 550 mV more positive than MOS <b>1</b>|GCE cathodes to reach the same activity for H<sub>2</sub> evolution from water (1 mA/cm<sup>2</sup>)

    Bioinspired Metal Selenolate Polymers with Tunable Mechanistic Pathways for Efficient H<sub>2</sub> Evolution

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    The efficient reduction of water into hydrogen has emerged as an attractive strategy for the conversion of solar energy into chemical bonds. Hydrogenase enzymes efficiently catalyze this reaction. The [NiFeSe] hydrogenases, a subclass of the [NiFe] hydrogenases with a selenocysteine replacing a cysteine residue, display higher activities and O<sub>2</sub> tolerance than the conventional sulfur-only [NiFe] hydrogenases. Inspired by the enhanced activity upon replacement of sulfur with selenium seen in nature, we report here the syntheses and characterization of cobalt and nickel selenolate coordination polymers (CPs) based on benzene-1,2,4,5-tetraselenolate (BTSe), which are efficient catalysts for the hydrogen evolution reaction (HER) from water. To reach a current density of 10 mA/cm<sup>2</sup>, the benchmarking metric for HER, both cobalt and nickel systems display overpotentials of only ∼350 mV, displaying a reduction in overpotential in comparison to the previously reported cobalt and nickel CPs based on benzene-1,2,4,5-tetrathiolate (BTT). In addition, the cobalt selenolate polymer displays a 217 mV improvement in the overpotential in comparison to its sulfur-only analogue that arises from the ability to promote an alternative mechanism at high catalyst loadings that was not available for the cobalt BTT CP

    Pendant Hydrogen-Bond Donors in Cobalt Catalysts Independently Enhance CO<sub>2</sub> Reduction

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    The bioinspired incorporation of pendant proton donors into transition metal catalysts is a promising strategy for converting environmentally deleterious CO<sub>2</sub> to higher energy products. However, the mechanism of proton transfer in these systems is poorly understood. Herein, we present a series of cobalt complexes with varying pendant secondary and tertiary amines in the ligand framework with the aim of disentangling the roles of the first and second coordination spheres in CO<sub>2</sub> reduction catalysis. Electrochemical and kinetic studies indicate that the rate of catalysis shows a first-order dependence on acid, CO<sub>2</sub>, and the number of pendant secondary amines, respectively. Density functional theory studies explain the experimentally observed trends and indicate that pendant secondary amines do not directly transfer protons to CO<sub>2</sub>, but instead bind acid molecules from solution. Taken together, these results suggest a mechanism in which noncooperative pendant amines facilitate a hydrogen-bonding network that enables direct proton transfer from acid to the activated CO<sub>2</sub> substrate

    Pendant Hydrogen-Bond Donors in Cobalt Catalysts Independently Enhance CO<sub>2</sub> Reduction

    No full text
    The bioinspired incorporation of pendant proton donors into transition metal catalysts is a promising strategy for converting environmentally deleterious CO<sub>2</sub> to higher energy products. However, the mechanism of proton transfer in these systems is poorly understood. Herein, we present a series of cobalt complexes with varying pendant secondary and tertiary amines in the ligand framework with the aim of disentangling the roles of the first and second coordination spheres in CO<sub>2</sub> reduction catalysis. Electrochemical and kinetic studies indicate that the rate of catalysis shows a first-order dependence on acid, CO<sub>2</sub>, and the number of pendant secondary amines, respectively. Density functional theory studies explain the experimentally observed trends and indicate that pendant secondary amines do not directly transfer protons to CO<sub>2</sub>, but instead bind acid molecules from solution. Taken together, these results suggest a mechanism in which noncooperative pendant amines facilitate a hydrogen-bonding network that enables direct proton transfer from acid to the activated CO<sub>2</sub> substrate

    The Reaction Mechanism of the Enantioselective Tsuji Allylation: Inner-Sphere and Outer-Sphere Pathways, Internal Rearrangements, and Asymmetric C–C Bond Formation

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    We use first principles quantum mechanics (density functional theory) to report a detailed reaction mechanism of the asymmetric Tsuji allylation involving prochiral nucleophiles and nonprochiral allyl fragments, which is consistent with experimental findings. The observed enantioselectivity is best explained with an inner-sphere mechanism involving the formation of a 5-coordinate Pd species that undergoes a ligand rearrangement, which is selective with regard to the prochiral faces of the intermediate enolate. Subsequent reductive elimination generates the product and a Pd<sup>0</sup> complex. The reductive elimination occurs via an unconventional seven-centered transition state that contrasts dramatically with the standard three-centered C–C reductive elimination mechanism. Although limitations in the present theory prevent the conclusive identification of the enantioselective step, we note that three different computational schemes using different levels of theory all find that inner-sphere pathways are lower in energy than outer-sphere pathways. This result qualitatively contrasts with established allylation reaction mechanisms involving prochiral nucleophiles and prochiral allyl fragments. Energetic profiles of all reaction pathways are presented in detail

    The Reaction Mechanism of the Enantioselective Tsuji Allylation: Inner-Sphere and Outer-Sphere Pathways, Internal Rearrangements, and Asymmetric C–C Bond Formation

    No full text
    We use first principles quantum mechanics (density functional theory) to report a detailed reaction mechanism of the asymmetric Tsuji allylation involving prochiral nucleophiles and nonprochiral allyl fragments, which is consistent with experimental findings. The observed enantioselectivity is best explained with an inner-sphere mechanism involving the formation of a 5-coordinate Pd species that undergoes a ligand rearrangement, which is selective with regard to the prochiral faces of the intermediate enolate. Subsequent reductive elimination generates the product and a Pd<sup>0</sup> complex. The reductive elimination occurs via an unconventional seven-centered transition state that contrasts dramatically with the standard three-centered C–C reductive elimination mechanism. Although limitations in the present theory prevent the conclusive identification of the enantioselective step, we note that three different computational schemes using different levels of theory all find that inner-sphere pathways are lower in energy than outer-sphere pathways. This result qualitatively contrasts with established allylation reaction mechanisms involving prochiral nucleophiles and prochiral allyl fragments. Energetic profiles of all reaction pathways are presented in detail
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