Amorphous Calcium Carbonate Cluster Nanospheres in Water-Deficient Organic Solvents.

As the key intermediate phase of crystalline calcium carbonate biominerals, amorphous calcium carbonate (ACC) remains mysterious in its structures because of its long-range disorder and instability. We herein report the synthesis of ACC nanospheres in a water-deficient organic solvent system. The obtained ACC nanospheres are very stable under dry conditions. Cryo-TEM reveals that each nanospheres consists of smaller nanosized clusters. We further demonstrate that these clusters can precipitate on other substrates to form an ultrathin ACC coating, which should be an ACC cluster monolayer. The results demonstrate that the presence of small ACC clusters as the subunits of larger aggregates is inherent to ACC synthesized in water-alcohol system but not induced by polymer additives.

Synthesis of PdSx-Mediated Polydymite Heteronanorods and Their Long-Range Activation for Enhanced Water Electroreduction.

Material interfaces permit electron transfer that modulates the electronic structure and surface properties of catalysts, leading to radically enhanced rates for many important reactions. Unlike conventional thoughts, the nanoscale interfacial interactions have been recently envisioned to be able to affect the reactivity of catalysts far from the interface. However, demonstration of such unlocalized alterations in existing interfacial materials is rare, impeding the development of new catalysts. We report the observation of unprecedented long-range activation of polydymite Ni3S4 nanorods through the interfacial interaction created by PdSx nanodots (dot-on-rod structure) for high-performance water catalytic electroreduction. Experimental results show that this local interaction can activate Ni3S4 rods with length even up to 25 nanometers due to the tailored surface electronic structure. We anticipate that the long-range effect described here may be also applicable to other interfacial material systems, which will aid the development of newly advanced catalysts for modern energy devices.

Phase-Selective Syntheses of Cobalt Telluride Nanofleeces for Efficient Oxygen Evolution Catalysts.

Cobalt-based nanomaterials have been intensively explored as promising noble-metal-free oxygen evolution reaction (OER) electrocatalysts. Herein, we report phase-selective syntheses of novel hierarchical CoTe2 and CoTe nanofleeces for efficient OER catalysts. The CoTe2 nanofleeces exhibited excellent electrocatalytic activity and stablity for OER in alkaline media. The CoTe2 catalyst exhibited superior OER activity compared to the CoTe catalyst, which is comparable to the state-of-the-art RuO2 catalyst. Density functional theory calculations showed that the binding strength and lateral interaction of the reaction intermediates on CoTe2 and CoTe are essential for determining the overpotential required under different conditions. This study provides valuable insights for the rational design of noble-metal-free OER catalysts with high performance and low cost by use of Co-based chalcogenides.