An earth-abundant catalyst-based seawater photoelectrolysis system with 17.9% solar-to-hydrogen efficiency

The implementation of water splitting systems, powered by sustainable energy resources, appears to be an attractive strategy for producing high-purity H2 in the absence of the release of carbon dioxide (CO2 ). However, the high cost, impractical operating conditions, and unsatisfactory efficiency and stability of conventional methods restrain their large-scale development. Seawater covers 70% of the Earth's surface and is one of the most abundant natural resources on the planet. New research is looking into the possibility of using seawater to produce hydrogen through electrolysis and will provide remarkable insight into sustainable H2 production, if successful. Here, guided by density functional theory (DFT) calculations to predict the selectivity of gas-evolving catalysts, a seawater-splitting device equipped with affordable state-of-the-art electrocatalysts composed of earth-abundant elements (Fe, Co, Ni, and Mo) is demonstrated. This device shows excellent durability and specific selectivity toward the oxygen evolution reaction in seawater with near 100% Faradaic efficiency for the production of H2 and O2 . Powered by a single commercial III-V triple-junction photovoltaic cell, the integrated system achieves spontaneous and efficient generation of high-purity H2 and O2 from seawater at neutral pH with a remarkable 17.9% solar-to-hydrogen efficiency.NRF (Natl Research Foundation, S’pore)ASTAR (Agency for Sci., Tech. and Research, S’pore)MOE (Min. of Education, S’pore

Controlling the Sulfidation Process of Iron Nanoparticles: Accessing Iron-Iron Sulfide Core-Shell Structures

Iron sulfide nanocomposites have been prepared through reactions of bis[bis(trimethylsilyl)amido]iron(II) or zerovalent iron nanoparticles (NPs) with hydrogen sulfide gas. The chemical composition of these materials was analyzed by TEM, XRD, WAXS and Mössbauer measurements. Decomposition of bis[bis(trimethylsilyl)amido]iron(II) under an H2S atmosphere in the presence of palmitic acid produces thin iron sulfide nanoflakes, which seemingly consist of Fe2S2 and Fe7S8. The sulfidation of 9 nm zerovalent iron NPs with H2S yields thin nano flakes exhibiting the same iron sulfide phases and residual iron. Remarkably, treatment of slightly larger iron NPs (13 nm) with H2S (or alternatively benzylthiol) yields well‐shaped iron–iron sulfide core‐shell particles. These particles exhibit a crystalline iron core and an amorphous iron sulfide shell, which likely consists of Fe2S2, Fe7S8 and Fe1−XS. Magnetic measurements on these core‐shell particles show a decrease of the total magnetization (compared to bulk iron) coming along with the sulfidation process. Owing to the partially preserved ferromagnetic character these iron–iron sulfide core‐shell particles were found to have magnetic heating properties