After a great research on CO 2 electroreduction catalysts, scientists found that copper (Cu) is the only metal that can reduce CO 2 into C 2+ products. However, Cu itself usually has poor selectivity due to the wide product distribution, which limits their potential application in CO 2 RR. [3] Extensive distinguished works have been devoted to regulating the selectivity of Cu catalysts, such as optimizing crystal facets, [4] alloying, [5] modifying oxidation state, [6] surface doping, [7] introducing defects, [8] and modifying ligand. [9] Even so, the reduction of CO 2 into C 2+ products with high selectivity is still a challenging work. Thus, the rational design and preparation of efficient catalysts hold great importance in their fundamental study as well as the technical advancement of CO 2 RR.It is widely accepted that CO related intermediates are the key species to C 2+ products in CO 2 RR. [10] Therefore, the designing of a two-step route (i.e., CO 2 to CO and CO to C 2+ ) provides an appropriate pathway for the highly selective conversion of CO 2 to C 2+ , which can be achieved by the fabrication of tandem catalysts with multicomposite or hierarchical structure. [11] For multicomposite catalysts, a synergistic effect between different components can be used to achieve in situ CO generation, promoting the subsequently reduced to C 2+ . Due to the excellent CO formation ability of Au and Ag, [12] many studies revealed that the combining Au or/and Ag with Cu could significantly improve the selectivity of C 2+ products for CO 2 RR. Many composite catalysts, such as Au-bipy-Cu, [13] Au/Cu, [14] Cu nanowire/Ag nanoparticles (NPs), [15] layered Cu/Ag, [16] Ag@Cu NPs, [17] Cu 500 Ag 1000 , [18] Ag 1 -Cu 1.1 , [19] and Cu-Au/Ag nanoframes, [20] have been developed. In addition to the composition control, the finely engineered structure of the catalysts can also improve their performance. Among them, the fabrication of core-shell structure has been verified to be an effective strategy to boost the performance of nanomaterials through the short diffusion path, high active surface area, low internal resistance, and excellent stability. [21] Therefore, core-shell nanomaterials are appealing as electrocatalysts since the core materials are the main active component with specific functions, while the shell materials act as protective layers to Electrochemical CO 2 reduction reaction (CO 2 RR) is critical to converting CO 2 to high-value multicarbon chemicals. However, the Cu-based catalysts as the only option to reduce CO 2 into C 2+ products suffer from poor selectivity and low activity. Tandem catalysis for CO 2 reduction is an efficient strategy to overcome such problems. Here, Cu@Ag core-shell nanoparticles (NPs) with different silver layer thicknesses are fabricated to realize the tandem catalysis for CO 2 conversion by producing CO on Ag shell and further achieving C-C coupling on Cu core. It is found that Cu@Ag-2 NPs with the proper thickness of Ag shell exhibit the Faradaic efficiency (FE) of total C 2 products ...

An eco-benign catalytic system in which Mn-doped bismuth oxyiodide (BiOI) was combined with H-ZSM-5 as a catalyst for direct hydrolysis and oxidation of cellulose into glycolic acid at 180 °C in an O 2 atmosphere achieved excellent catalytic performance with a yield of 82.6%. The prominent catalytic performance was largely attributed to the synergistic effect between Mn species with BiOI and the stronger Brønsted acid sites over H-ZSM-5. Furthermore, the as-synthesized catalyst displayed extraordinary catalytic performance after five successive reaction runs. Most importantly, this study provides an eco-friendly strategy to design efficient heterogeneous catalysts for converting biomass resources into biofuels and high-value-added chemicals.

Lactic acid is a versatile and potential building block for generating biodegradable plastics and polylactic acid, as well as in chemical and pharmaceuticals industry. Nevertheless, the achievement of lactic acid production in large quantities remains an enormous challenge. Herein, a series of yttriummodified composite metal oxide catalysts were synthesized for production of lactic acid starting from renewable biomass cellulose. Interestingly, Y 2 O 3 /Al 2 O 3 showed outstanding chemoselectivity towards lactic acid due to its predominant Lewis acid sites (Y 3 + ) and weak Brønsted acid sites (hydroxyl group) together with appropriate total surface acidity. The structure-activity relationship was systematically investigated by a combination of XRD, BET, NH 3 -TPD, PyIR, SEM, FTIR, and XPS characterization techniques. A nearly complete conversion of cellulose and as high as 72.8 % yield of lactic acid could be achieved under the optimum conditions. Importantly, the resultant catalysts were reusable without appreciable loss in catalytic activity after five consecutive cycles. This study provides an efficient, cost-efficient and facile strategy for fabricating promising heterogeneous catalysts for conversion of biomass resources to highly valuable chemicals.

Catalytic conversion of cellulose to liquid fuel and highly valuable platform chemicals remains a critical and challenging process. Here, bismuth-decorated β zeolite catalysts (Bi/β) were exploited for highly efficient hydrolysis and selective oxidation of cellulose to biomass-derived glycolic acid in an O2 atmosphere, which exhibited an exceptionally catalytic activity and high selectivity as well as excellent reusability. It was interestingly found that as high as 75.6% yield of glycolic acid over 2.3 wt% Bi/β was achieved from cellulose at 180 °C for 16 h, which was superior to previously reported catalysts. Experimental results combined with characterization revealed that the synergetic effect between oxidation active sites from Bi species and surface acidity on H-β together with appropriate total surface acidity significantly facilitated the chemoselectivity towards the production of glycolic acid in the direct, one-pot conversion of cellulose. This study will shed light on rationally designing Bi-based heterogeneous catalysts for sustainably generating glycolic acid from renewable biomass resources in the future.