Small amount of Se atoms are used to tune the carrier concentrations (nH) and electrical transport in Ag2Se. Significant enhancements in power factor and thermoelectric figure of merit (zT) are observed in the compositions of Ag2Se1.06 and Ag2Se1.08. The excessive Se atoms do not change the intrinsically electron-conducting character in Ag2Se. The detailed analysis reveals the experiment optimum carrier concentration in Ag2Se is around 5 × 1018 cm−3. We also investigate the temperature of maximum zT and the thermoelectric transport during the first order phase transitions using the recently developed measurement system.

The dehydration mechanisms for glucose in β-pyranose (BP) and in open-chain (OC) forms, catalyzed by acids homogeneously and heterogeneously, were investigated using density functional and two-layer ONIOM calculations. The first dehydration reaction and competing reaction pathways are the main focus of the present study. The energetics of five dehydration and two isomerization pathways were examined for the protonated form of BP in acidic aqueous solutions and the most favorable pathway of these was found to be the dehydration at the anomeric site. No dehydration pathway of OC glucose is favored over its isomerization to BP or to fructose. The relative ease of dehydration over isomerization depends on the selection of the reaction media for the protonated form of BP. These two reaction pathways catalyzed by a surface Brönsted acid site were then examined and the isomerization pathway was found to be more favorable than dehydration at the anomeric site on a surface acid site. These mechanistic insights provide an important guide for the catalyst design/selection of the reaction media for glucose dehydration.

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Sequential two-layer catalysts were used for the hydrogenolysis of glycerol to remove its oxygen content in a continuous-flow fixed-bed reactor. The acidic H-β catalyst layer was packed before the Ni/Al2O3 catalyst layer in the reactor. The sequential two-layer catalysts can provide good 1-propanol (1-PO) selectivities at high glycerol conversions (up to 69% selectivity at ∼100% conversion). To our knowledge, the catalytic system in this work presented one of the best selectivities to 1-PO using non-noble metal based catalytic systems. A preliminary mechanistic study indicated that most of 1-PO in the products was generated from glycerol via a “sequential two-time dehydration-hydrogenation” mechanism.