Reduction of CO2 to methanol using renewable hydrogen is a promising but challenging strategy for carbon capture and utilization.

Conversion of CO 2 to value-added chemicals has been a long-standing objective, and direct hydrogenation of CO 2 to lower olefins is highly desirable but still challenging. Herein, we report a selective conversion of CO 2 to lower olefins through CO 2 hydrogenation over a ZnZrO/SAPO tandem catalyst fabricated with a ZnO-ZrO 2 solid solution and a Zn-modified SAPO-34 zeolite, which can achieve a selectivity for lower olefins as high as 80−90% among hydrocarbon products. This is realized on the basis of the dual functions of the tandem catalyst: hydrogenation of CO 2 on the ZnO-ZrO 2 solid solution and lower olefins production on the SAPO zeolite. The thermodynamic and kinetic coupling between the tandem reactions enable the highly efficient conversion of CO 2 to lower olefins. Furthermore, this catalyst is stable toward the thermal and sulfur treatments, showing the potential industrial application.

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Spatially resolved surface photovoltage spectroscopy (SRSPS) was employed to obtain direct evidence for highly anisotropic photogenerated charge separation on different facets of a single BiVO4 photocatalyst. Through the controlled synthesis of a single crystal with preferentially exposed {010} facets, highly anisotropic photogenerated hole transfer to the {011} facet of single BiVO4 crystals was observed. The surface photovoltage signal intensity on the {011} facet was 70 times stronger than that on the {010} facets. The influence of the built-in electric field in the space charge region of different facets on the anisotropic photoinduced charge transfer in a single semiconductor crystal is revealed.

While calcium oxide has been identified to be the best candidate for capturing CO 2 at high temperature, it suffers a well-known problem of loss-in-capacity; that is, its capacity for carbon capture decays dramatically during cyclic carbonation/ calcination processes. Recently, extensive research work has been conducted on the enhancement of the cyclic performance of calcium oxide through either improving the performance of natural minerals, such as water/steam hydration and pretreatment or modification of calcium oxide sorbents by some techniques such as doping and synthesis. This work summarizes the state-of-theart research in the literature aiming to identify potential solutions to the loss-in-capacity problem. It is found that hydration during or after calcination is effective in recovering the capacity of natural minerals and mixing can produce highly effective synthetic sorbents. Periodic hydration of synthetic sorbents could be a good strategy to overcome the technical issues associated with loss-in-capacity while meeting the requirements of the physical properties of sorbents in many potential applications.

The electrocatalytic carbon dioxide (CO 2 )reduction reaction (CO 2 RR) into hydrocarbons is apromising approach for greenhouse gas mitigation, but many details of this dynamic reaction remain elusive.Here,time-resolved surface-enhanced Raman spectroscopy( TR-SERS) is employed to successfully monitor the dynamics of CO 2 RR intermediates and Cu surfaces with sub-second time resolution. Anodic treatment at 1.55 Vvs. RHE and subsequent surface oxide reduction (below À0.4 Vv s. RHE) induced roughening of the Cu electrode surface,w hich resulted in hotspots for TR-SERS,e nhanced time resolution (down to % 0.7 s) and fourfold improved CO 2 RR efficiency toward ethylene.W ithT R-SERS,t he initial restructuring of the Cu surface was followed (< 7s), after which astable surface surrounded by increased local alkalinity was formed. Our measurements revealed that ahighly dynamic CO intermediate,w ith ac haracteristic vibration below 2060 cm À1 ,isrelated to CÀCcoupling and ethylene production (À0.9 Vv s. RHE), whereas lower cathodic bias (À0.7 Vv s. RHE) resulted in gaseous CO production from isolated and static CO surface species with adistinct vibration at 2092 cm À1 .

The global warming issue has resulted in a great demand in zero emission power generation systems. Recently a few new concepts have been proposed that promise to achieve zero emissions while delivering unprecedentedly high efficiency. In these concepts, CO2 adsorbing material (CAM) is a key component. This paper reviews briefly the current development in CO2 adsorbing material, screens the potential materials under the conditions relevant to those in zero emission power generation systems, and identifies the best candidate and the optimum operating conditions for the production of high-purity hydrogen. It is found that CaO is thermodynamically the best candidate among metal oxides for CO2 capture in zero emission power generation systems. There exists a region within which high-purity H2 can be produced in steam methane reforming and carbon gasification.

The cocatalysts or dual cocatalysts of photocatalysts are indispensable for high efficiency in artificial photosynthesis for solar fuel production. However, the reaction activity increased by cocatalysts cannot be directly ascribed to the accelerated catalytic kinetics, since photogenerated charges are involved in the elementary steps of photocatalytic reactions. To date, diverging views about cocatalysts show that their exact role for photocatalysis is not well understood yet. Herein, we image directly the local separation of photogenerated charge carriers across single crystals of the BiVO photocatalyst which loaded locally with nanoparticles of a MnO single cocatalyst or with nanoparticles of a spatially separated MnO and Pt dual cocatalyst. The deposition of the single cocatalyst resulted not only in a strong increase of the interfacial charge transfer but also, surprisingly, in a change of the direction of built-in electric fields beneath the uncovered surface of the photocatalyst. The additive electric fields caused a strong increase of local surface photovoltage signals (up to 80 times) and correlated with the increase of the photocatalytic performance. The local electric fields were further increased (up to 2.5 kV·cm) by a synergetic effect of the spatially separated dual cocatalysts. The results reveal that cocatalyst has a conclusive effect on charge separation in photocatalyst particle by aligning the vectors of built-in electric fields in the photocatalyst particle. This effect is beyond its catalytic function in thermal catalysis.