A series of pyridine-type ligands containing C≡C bonds were designed and synthesized for selective oxidative Heck reaction. These ligands were utilized as functional units and integrated into the skeleton of conjugated microporous polymers. 6,6'-diiodo-2,2'-bipyridine and 1,3,5-triethynylbenzene were polycondensed via Sonogashira cross-coupling strategy to afford CMP-1 material. The resultant CMP-1 was used as a heterogeneous catalytic ligand for the Pd-catalyzed oxidative Heck reaction with high linear selectivity. The linear selectivity of CMP-1 is about 30 times higher than that of bipyridine-based monomer ligand. This work opens a new front of using CMP as an intriguing platform for developing highly efficient catalysts in controlling the regioselectivity in organic reactions.

Crystal facet engineering of semiconductors has been proven to be an effective strategy to increase photocatalytic performances. However, the mechanism involved in the photocatalysis is not yet known. Herein, we report our success in that photocatalytic performances of the Cl(-) ion capped CoO octahedrons with exposed {111} facets were activated by a treatment using AgNO3 and NH3·H2O solutions. The clean CoO {111} facets were found to be highly reactivity faces. On the basis of the polar structure of the exposed {111} surfaces, a charge separation model between polar {111} surfaces is proposed. There is an internal electric field between polar {111} surfaces due to the spontaneous polarization. The internal electric field provides a driving force for charge separation. The reduction and oxidation reactions selectively take place on the positive and negative polar {111} surfaces. The charge separation model provides a clear insight into charge transfer in the semiconductor nanocrystals with high photocatalytic activities and offer guidance to design more effective photocatalysts, solar cells, photoelectrodes, and other photoelectronic devices.

The search for active narrow band gap semiconductor photocatalysts that directly split water or degrade organic pollutants under solar irradiation remains an open issue. We synthesized Cu2Se nanowires with exposed {111} facets using ethanol and glycerol as morphology controlling agents. The {111} facets were found to be the active facets for decomposing organic contaminants in the entire solar spectrum. Based on the polar structure of the Cu2Se {111} facets, a charge separation model between polar (111) and (1[combining macron]1[combining macron]1[combining macron]) surfaces is proposed. The internal electric field between polar (111) and (1[combining macron]1[combining macron]1[combining macron]) surfaces created by spontaneous polarization drives charge separation. The reduction and oxidation reactions occur on the positive (111) and negative (1[combining macron]1[combining macron]1[combining macron]) polar surfaces, respectively. This suggests the surface-engineering of narrow band gap semiconductors as a strategy to fabricate photocatalysts with high reactivity in the entire solar spectrum. The charge separation model can deepen the understanding of charge transfer in other semiconductor nanocrystals with high photocatalytic activities and offer guidance to design more effective photocatalysts as well as new types of solar cells, photoelectrodes and photoelectric devices.

It is rather challenging to develop photocatalysts based on narrow-band-gap semiconductors for water splitting under solar irradiation. Herein, we synthesized the CuO/CuSe multilayer heterostructure nanowires exposing {111} crystal facets by a hydrothermal reaction of Se with Cu and KBH in ethanol amine aqueous solution and subsequent annealing in air. The photocatalytic H production activity of CuO/CuSe multilayer heterostructure nanowires is dramatically improved, with an increase on the texture coefficient of CuO(111) and CuSe(111) planes, and thus the exposed {111} facets may be the active surfaces for photocatalytic H production. On the basis of the polar structure of CuO {111} and CuSe {111} surfaces, we presented a model of charge separation between the Cu-CuSe(111) and O-CuO(1̅ 1̅ 1̅) polar surfaces. An internal electric field is created between Cu-CuSe(111) and O-CuO(1̅ 1̅ 1̅) polar surfaces, because of spontaneous polarization. As a result, this internal electric field drives the photocreated charge separation. The oxidation and reduction reactions selectively occur at the negative O-CuO(1̅ 1̅ 1̅) and the positive Cu-CuSe(111) surfaces. The polar surface-engineering may be a general strategy for enhancing the photocatalytic H-production activity of semiconductor photocatalysts. The charge separation mechanism not only can deepen the understanding of photocatalytic H production mechanism but also provides a novel insight into the design of advanced photocatalysts, other photoelectric devices, and solar cells.

Herein, we developed an [001] orientated ZnO thin film photovoltaic device without p–n junction. On the basis of the presence of the internal electric field in ZnO thin film, we proposed a new physical mechanism of photon-to-electron conversion.

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Heterogeneously and uniformly dispersed metal nanoclusters with high thermal stability and stable nonmetallic nature show outstanding catalytic performance. In this work, we report on the role of sulfur moieties in hydrochlorination catalysis over carbon-supported gold (Au/C). A combination of experimental and theoretical analyses shows that the −SO3H and derived −SO2H sulfur species in high oxidation states at the interface between Au and −SO3H at ≥180 °C give rise to high thermal stability and catalytic activity. By contrast, the grafted thiol group (−SH) and the derived low-valence sulfur species on carbon markedly destabilize the Au nanoclusters, promoting their rapid sintering into large Au nanoparticles and leading to the loss of their cationic nature. Theoretical calculations suggest that −SO3H favorably adsorbs and stabilizes cationic Au species. Compared to Au/C and Au–SH/C with the Auα+/Au0 atomic ratios of 1.02 and 0.24, respectively (α = 1 or 3), the activity and durability of acetylene hydrochlorination are remarkably enhanced by the interaction between the −SO3H moieties and cationic Au species that enables the high oxidation state of Au to be effectively retained (Auα+/Au0 = 3.82). These results clearly demonstrate the double-edged sword effect of sulfur moieties on the catalytic Au component in acetylene hydrochlorination. The double-edged sword effect of sulfur species in the stabilization/destabilization of metal nanoclusters is also applicable to other metals such as Ru, Pd, Pt, and Cu. Overall, this study enriches the general understanding of the stabilization of metal clusters and provides insight into a wet chemistry strategy for stabilizing supported ligand-free nanoclusters.