Search

The achievement of excellent catalytic activity for electricity‐driven CO2 reduction over a wide potential window is significant for the mature applications. However, the efficient potential range is always limited by the dilemma in CO2 activation and product desorption at different potentials, due to the scaling relationships of adsorption energy. Herein, we developed a nanostructured Ag‐CO3 electrocatalyst featuring metallic Ag with Ag(220) orientation on the surface and Ag2CO3 beneath. The interactions between Ag and Ag2CO3 lead to lattice expansion on the surface of Ag, resulting in electron localization and accordingly enhanced CO2 activation to *COOH on Ag. Furthermore, this lattice expansion induces a change in the *CO adsorption geometry from a bridge mode to a linear mode, which compensates the promotion effect of electron localization on *CO adsorption energy. As a result, the scaling relationship between *COOH and *CO adsorption energy was disrupted, leading to enhanced *COOH adsorption and inferior *CO adsorption. Consequently, the Ag‐CO3 catalyst exhibited a high FECO (>80%) over a robust potential window of −0.8 to −1.8 V (vs. RHE), with a maximum FECO of 95% at −1.2 V (vs. RHE). The mechanism described herein offers a universal design principle for the development of high‐efficiency CO2 electroreduction catalysts that operate effectively within a broad potential range. [ABSTRACT FROM AUTHOR]

Rational screening of efficient supported metal catalysts is still a great challenge due to the complicated reaction mechanism for selective polyol oxidation. Exemplifying glycerol oxidation to glyceric acid as a model reaction, we perform a DFT assisted descriptor based microkinetic modeling to reveal the underlying mechanism. It is found that the addition/formation of OH− could polarize the metal surface (M‐OH*) to regulate the d‐band center of Pt accompanied by the electron transfer from OH− to metal atoms, thus promoting the adsorption of glycerol. Moreover, the linear chemisorption energy and transition state energy scaling relations are well established on the formation energies of adsorbed C and O. Activity map obtained from descriptor based microkinetic analysis demonstrates that Pt and Ir metals exhibit the highest catalytic activity. Meanwhile, further analysis of the desorption energy and CC bond cleavage activation energy of glyceric acid product shows that Au and Pt metals display the optimal glyceric acid selectivity. Satisfactorily, these results from microkinetic analysis are in good agreement with the comparative experimental results. The insights revealed here may open a new avenue for rational design of transition metal catalysts in the bio‐polyol oxidation system. [ABSTRACT FROM AUTHOR]

Simultaneous transformation of CO2 and H2O into syngas (CO and H2) using solar power is desirable for industrial applications. Herein, an efficient photocatalyst based on double‐shelled nanoboxes, with an outer shell of hydroxy‐rich nickel cobaltite nanosheets and an inner shell of Cu2S (Cu2S@ROH‐NiCo2O3), is prepared via a multistep templating strategy. The high performance of Cu2S@ROH‐NiCo2O3 (7.1 mmol g−1 h−1 for CO; 2.8 mmol g−1 h−1 for H2) is attributed to the hierarchical hollow geometry and p–n heterojunction to promote light absorption and charge separation. Spectroscopic and theoretical analyses elucidate that the ROH‐NiCo2O3 surface enhances *CO2 adsorption and lowers energy barriers for CO2‐to‐CO. Therefore, modulating the hydroxy contents of ROH‐NiCo2O3 can achieve broad CO/H2 ratios from 0.51 to 1.24. This work offers in‐depth insights into adjustable syngas photosynthesis and generalized concepts of selective heterogeneous CO2 photoreduction beyond cobalt‐based oxides. [ABSTRACT FROM AUTHOR]

The defect plays a significant role in tuning the electronic structure of metal compounds such as oxides, chlorides, sulfides and nitrides, which is frequently used to explain the enhanced catalytic activity. However, the dynamic change of defect relating to the oxidation state change during the reaction is rarely addressed, and it is still not able to be appropriately predicted since the kinetic modeling of the redox reaction involving the in‐situ formation of defects is challenged by the dynamic evolution of the active sites and the complex kinetic phenomena. Here, for the first time, we present a general method to build a new kinetic model of the redox reaction cycle by combined kinetics of reduction‐ and oxidation steps to predict the time and spatially resolved formation of defects of solid catalysts and the reaction products in ethylene oxychlorination on CuCl2/Al2O3 catalyst. The defect concentration can be tuned by manipulating the relative rates of the reduction‐ and oxidation steps. [ABSTRACT FROM AUTHOR]

A ZnO-nanolayer-coated carbon nanotube (CNT) composite (ZnO-CNT) was employed as a support to immobilise Ni catalysts. Well-mixed oxides, formed as a result of enhanced interfaces between the two oxides on CNTs, resulted in the formation of Ni-Zn alloys in reduced catalysts. The Ni/ZnO-CNT catalyst exhibited much higher yields of vicinal diols, for example, ethylene glycol and 1,2-propylene glycol, from the conversion of cellulose than the reference Ni/CNT catalyst. A plausible reaction network on the Ni/ZnO-CNT catalyst has been proposed. Moreover, the effects of Ni loading and catalyst reduction temperature on the catalytic performance were probed, and the relationship between the catalyst structure and the yields of vicinal diols was correlated. The Ni-rich alloy, relative to the Zn-rich alloy, was suggested as the dominating active phase for the selective conversion of cellulose into vicinal diols. This might shed new light on the design and optimisation of Ni-based catalysts for the catalytic conversion of cellulose with the Ni-Zn interaction. [ABSTRACT FROM AUTHOR]