Enhanced ethanol electro-oxidation on CeO 2 -modified Pt/Ni catalysts in alkaline solution

Zeolitic Imidazolate Framework-67-Derived P-Doped Hollow Porous Co3O4 as a Photocatalyst for Hydrogen Production from Water

As a part of photocatalytic water splitting, the design of low-cost, high-activity catalysts plays an essential role in the development of photocatalytic water splitting. Metal oxides have the advantages of a wide range of sources, many varieties, and easy preparation. Doping engineering on their surface can construct new active sites and adjust their catalytic activity. In this work, a new strategy was developed through anion hybridization to regulate electron delocalization. Using one of the cobalt-based zeolitic imidazole skeletons (ZIF-67) as a precursor material, a two-step calcination method was used to prepare a P-doped Co₃O₄ mixed anion composite photocatalyst. The hydrogen production rate of P@Co₃O₄ is 39 times that of ZIF-67 and 6.8 times that of Co₃O₄. Through density functional theory (DFT) calculations, the electron delocalization state of the sample surface is predicted and the reaction energy barrier is reduced to promote the process of the hydrogen evolution reaction (HER). The special O(δ-)-Co(δ+)-P(δ-) surface bonding state promotes the bridging of isolated electronic states and provides active sites for the adsorption and activation of reaction substrates. The improved electron transport pathway and the synergy between the catalytic sites under the high electron transport rate are the main reasons for the enhanced photocatalytic hydrogen evolution activity. This strategy, including changing the surface bond state and optimizing the structure and composition of the catalyst not only provides a new method for preparing other MOF-derived nanomaterials with porous structures but also inspires the reasonable development of other MOF-based advanced photocatalysts.

NiCo LDH in situ derived NiCoP 3D nanoflowers coupled with a Cu3P p-n heterojunction for efficient hydrogen evolution

With the extensive consumption of non-renewable energy sources, storing solar energy as chemical energy has aroused people's wide concern. In this study, we successfully developed a novel Cu₃P@NiCoP composite photocatalyst to produce hydrogen by splitting water under visible light irradiation. Both the building of a p-n heterojunction between Cu₃P and NiCoP and the three-dimensional nanoflower structure of NiCoP play a vital role in improving the performance of the catalyst. On the one hand, the coupling of Cu₃P and NiCoP built a p-n heterojunction at the photocatalyst interface, and the heterojunction could promote the separation efficiency of photogenerated carriers and prolong the life span of charges, therefore enhancing the photocatalytic hydrogen production activity. On the other hand, the excellent catalytic performance of the photocatalyst was benefited by the flower-like microsphere structure of NiCoP, which could provide abundant active sites and a large specific surface area, and promote the adsorption of protons by the photocatalyst. Besides, the phosphating degree of the precursors and the ratio of Cu₃P and NiCoP were adjusted to get the best photocatalyst for hydrogen production, and the H₂ production of the optimal catalyst could reach 8897.44 μmol h^-1 g^-1. This work provides a new understanding for the rational design of heterojunction photocatalysts for outstanding hydrogen production performance.

Investigation of electrocatalytic activity of NiTPPBr6 on the graphite electrode for oxidation of methanol, ethanol, 1-propanol and 2-propanol

Due to the importance of producing clean energy through systems such as alcoholic fuel cell, methanol, ethanol, 1-propanol, and 2-propanol, these alcohols were oxidized at the modified graphite electrode by NiTPPBr6 / NiTPPBr8 as a clean electrocatalyst in an alkaline media. This process investigated by various techniques such as cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS), in all cases showed Cottrell type behavior with the diffusion of coefficients of 2.04 × 10[Formula: see text], 1.3 × 10[Formula: see text] 8.3 × 10[Formula: see text] cm[Formula: see text] s[Formula: see text] for the corresponding alcohols respectively. Likewise, the catalytic rate constant for methanol oxidation was found to be 2.9 × 108 cm3mol[Formula: see text] s[Formula: see text] through chronoamperometric measurements. Interestingly, the order in activity for oxidation of the alcohols introduced with the electrocatalyst was: 2-propanol [Formula: see text] 1-propanol [Formula: see text] ethanol [Formula: see text] methanol and was unlike previous studies in which the oxidation current was reduced by increasing the number of carbon atoms from methanol to propanol.

Theoretically guiding the construction of a novel Cu2O@Cu97P3@Cu3P heterojunction with a 3D hierarchical structure for efficient photocatalytic hydrogen evolution

Using photocatalysis to produce clean H2 energy has been considered as one of the ideal strategies to alleviate the energy crisis and environmental pollution. In this work, the density functional theory (DFT) calculation was used as a guide to determine the experimental scheme of surface modification of Cu2O with Cu3P. With Cu2O as the core and Cu3P as the shell, the precursor was constructed by electrostatic self-assembly at first. After secondary calcination, Cu97P3 was formed from the compact interface between Cu2O and Cu3P, thus the 3D hierarchical structure of Cu-O-P(Cu2O@Cu97P3@Cu3P) was successfully constructed. The generation of Cu97P3 significantly increases the photocatalytic H2 production of Cu2O@Cu97P3@Cu3P under visible light irradiation. The photocatalytic activity of the composite with optimal ratio increased about 17 times as much as that of pure Cu2O. The separation and transportation efficiency of its photogenerated charges has been significantly improved. The 3D hierarchical core-shell structure is not only beneficial to strengthen the interface contact between different semiconductors but also to improve the transferability of photogenerated electrons. Through a series of experimental results, the strategy has proved to be successful that Cu3P was introduced onto the surface of the Cu2O octahedron to change the adsorption free energy of H atoms, reduce the overpotential of hydrogen evolution, and increase the active sites of hydrogen production. At the same time, the isolated interfaces are integrated by calcination to obtain Cu97P3 bridged substances derived from the interfaces. The presence of Cu97P3 establishes a new fast channel for electron flow between semiconductors, significantly accelerates the transfer of electrons, and ultimately improves the performance of photocatalytic hydrogen evolution. This work provides new insights into the design and flexible synthesis of inexpensive copper-based nano-photocatalysts.

Novel S-scheme RP/NiCo-LDH composite with remarkably enhanced photocatalytic activity for H2 evolution under visible-light irradiation

A novel red phosphorus/nickel cobalt layered double hydroxide (RP/NiCo-LDH) heterojunction was successfully prepared and exhibited an excellent photocatalytic performance for hydrogen evolution.

Advanced Catalytic Materials for Ethanol Oxidation in Direct Ethanol Fuel Cells

Direct ethanol fuel cells (DEFCs) have emerged as promising and advanced power systems that can considerably reduce fossil fuel dependence, and thus have attracted worldwide attention. DEFCs have many apparent merits over the analogous devices fed with hydrogen or methanol. As the key constituents, the catalysts for both cathodes and anodes usually face some problems (such as high cost, low conversion efficiency, and inferior durability) that hinder the commercialization of DEFCs. This review mainly focuses on the most recent advances in nanostructured catalysts for anode materials in DEFCS. First, we summarize the effective strategies used to achieve highly active Pt- and Pd-based catalysts for ethanol electro-oxidation, including composition control, microstructure design, and the optimization of support materials. Second, a few non-precious catalysts based on transition metals (such as Fe, Co, and Ni) are introduced. Finally, we outline the concerns and future development of anode catalysts for DEFCs. This review provides a comprehensive understanding of anode catalysts for ethanol oxidation in DEFCs.