High strength inorganic-organic polymer composites (IOPC) manufactured by mold pressing of geopolymers

Inorganic-organic polymer composites (IOPCs) were manufactured from geopolymer and epoxy resin through mold pressing. The pore structure, hydration kinetic and microstructure of IOPCs are examined by mercury intrusion porosimetry (MIP), isothermal conduction calorimetry and scanning electron microscopy (SEM), respectively. When the epoxy resin content is 4 wt% and molding pressure value is 200 MPa, the optimal compressive strength of IOPCs after curing 3 days can reach to 116.3 MPa. The porosity of IOPCs is 22.48%. With the epoxy resin content increasing from 0 to 8 wt%, the porosity gradually increases and the pore size distribution first reduces and then increases. Increasing the content of epoxy resin within an appropriate range could increase the cumulative heat and fill the inner space inside the microstructure of geopolymer paste. When the epoxy resin content is less than 4 wt%, the pore size distribution shifts to smaller region, but which changes to larger region when the epoxy resin content is more than 4 wt%. The porosity, pore diameter and compressive strength meet a regressive equation

One-step in-situ sprouting high-performance NiCoSxSey bifunctional catalysts for water electrolysis at low cell voltages and high current densities

Engineering high-performance non-precious metal-based bifunctional catalysts for water splitting are still facing some issues especially at industry-relevant current densities. Here, this challenge is addressed by the new approach to grow extra-stable nickel cobalt sulfur-selenide (NiCoSxSey) nanosheet catalysts on nickel–cobalt foam (NCF), and the obtained NiCoSxSey affords the low overpotentials of 345 mV for hydrogen evolution reaction (HER) and 427 mV for oxygen evolution reaction (OER) at 1000 mA cm−2 (j1000). Meanwhile, the NiCoSxSey/NCF also shows the excellent long-term stability for both HER and OER processes driven with j100 for 100 h and j500 for 24 h. In addition, the cell voltage assembled with NiCoSxSey/NCF is only 1.84 V at j500 in 1 M KOH, and the I-t characteristic shows a low decay (100. The ab-initio simulations reveal that the CoS2-CoSe2, Ni3S2-Ni3Se2 and CoS2-Ni3Se2 interfaces are the active sites for HER

Compositional and crystallographic design of Ni-Co phosphide heterointerfaced nanowires for high-rate, stable hydrogen generation at industry-relevant electrolysis current densities

Lack of high-performance noble-metal free electrocatalysts for hydrogen evolution reaction (HER) to exceed the benchmark Pt-based electrocatalysts, still remains a major hurdle on the way to clean hydrogen economy. Here we rationally, atomistically design and synthesize the hetero-interfaced Ni-Co phosphide nanowires which deliver exceptional activity and stability in water electrolysis under industry-relevant current densities. The compositional and crystallographic design produces extra-stable Ni5P4-Co2P nanowires sprouting from a Ni-Co alloy foam (NCF). The extraordinary reactivity is ensured by the heterointerfaces between the highly-active (303) crystal planes of Co2P and Ni5P4 nanowire phases. The overpotentials of Ni5P4-Co2P/NCF catalysts at −10, −100, and −1000 mA cm−2 are about 21, 92 and 267 mV in 1 M KOH, respectively, far exceeding the commercial Pt/C catalysts. The Tafel slope of Ni5P4-Co2P/NCF catalyst is only 23 mV dec−1, indicating an even faster HER kinetic compared to Pt/C (32 mV dec−1). Moreover, the Ni5P4-Co2P/NCF catalyst shows an ultra-stable and lasting performance, evidenced by only a minor 3.6% drop at j250 after 100 h continuing operation. The DFT calculations confirm that the exposed heterointerfaces between (303) planes of Ni5P4 and Co2P phases play a key role for boosting the HER activity of Ni5P4-Co2P electrocatalyst.</p