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Catalytic transformation of CH4 under a mild condition is significant for efficient utilization of shale gas under the circumstance of switching raw materials of chemical industries to shale gas. Here, we report the transformation of CH4 to acetic acid and methanol through coupling of CH4, CO and O2 on single-site Rh1O5 anchored in microporous aluminosilicates in solution at ≤150 °C. The activity of these singly dispersed precious metal sites for production of organic oxygenates can reach about 0.10 acetic acid molecules on a Rh1O5 site per second at 150 °C with a selectivity of ~70% for production of acetic acid. It is higher than the activity of free Rh cations by >1000 times. Computational studies suggest that the first C–H bond of CH4 is activated by Rh1O5 anchored on the wall of micropores of ZSM-5; the formed CH3 then couples with CO and OH, to produce acetic acid over a low activation barrier.

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A surface/gas-phase reaction on TiO 2 (110) was visualized in situ by scanning tunneling microscopy. When a vacuum annealed ͑1 3 1͒ surface heated at 800 K was exposed to an O 2 ambient of 1 3 10 25 Pa, hill-like structures were randomly nucleated over terraces. Then they were transformed into new terraces, with added rows comprising double strands. We proposed a reoxidation scheme to interpret the dynamics; partially reduced Ti n1 ions ͑n # 3͒, which had been accumulated at interstitial positions in the vacuum annealed crystal, were oxidized at the surface to form the hills, added rows, and new terraces.

The structure transformation of a TiO2(110) surface was observed at atomic-scale resolution by scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED). Irregular corrugations on an argon-bombarded TiO2(110) surface crystallized to stacked (1 × 1) terraces by vacuum annealing at 600—800 K. The terraces grew in dimension to be as large as 30 × 30 nm2 at 900 K. The unoccupied surface states localized on individual Ti4+ ions were resolved on a (1 × 1) terrace. The position of the Ti4+ ions was probed by imaging adsorbed formate ions. Annealing at higher temperatures resulted in the formation of a wide row structure comprising double strands. Imaging of individual adsorbed formate ions was used to grade possible structure models by probing Ti ions exposed on the surface; thereby, an added Ti2O3 row model, which is a new surface-limited phase of titanium oxide consisting of Ti3+ ions of the optimum six-fold coordination, was concluded for the double-strand structure. These results demonstrate the ability of probing experiments with an adsorbed molecule to determine the chemical nature of imaged sites on multi-component materials by STM.

Hydrogen atoms adsorbed on TiO2(110)-(1x1) surfaces have been characterized by scanning tunneling microscopy (STM) combined with electron stimulated desorption (ESD) technique. Certain amounts of H atoms are unexpectedly found on the TiO2 surfaces annealed at 900 K. Two forms of adsorption were discriminated in STM images from the different sensitivity to ESD and tentatively assigned to hydroxyl-type (O-H) and hydride-type (Ti-H) species.

Hexagonally arranged surface oxygen atoms, oxygen point defects, and multiple oxygen defects at oxygen-terminated CeO2(111) surfaces in different oxidation states were visualized by noncontact atomic force microscopy (NC-AFM). The multiple defects such as line defects and triangular defects were stabilized by a local reconstruction, where edge oxygen atoms surrounding the multiple defects were displaced and gave enhanced brightness due to a geometric reason. Successive NC-AFM measurements of the same area of a slightly reduced CeO2(111) surface revealed that hopping of surface oxygen atoms faced to metastable multiple defects was thermally activated even at room temperature. In contrast, no hopping was observed either at a point oxygen vacancy or a line defect that is stabilized by local reconstruction. It was also confirmed from atom-resolved NC-AFM observations that the surface oxygen defects were easily healed by exposure to O2 gas at room temperature.