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Highlights: [•] Novel Ni2+–TiO2 photocatalysts were immobilized onto supports for CO2 photoreduction. [•] CO2 is photocatalytically reduced to fuels upon UV or visible light irradiation. [•] Fuel production rate and selectivity are enhanced upon nickel deposition. [ABSTRACT FROM AUTHOR]

Abstract: The transformation of CO2 using semiconductor photocatalysts is a promising alternative for developing sustainable energy sources. Nickel (Ni) based TiO2 photocatalysts immobilized onto quartz plate was assembled in a unique reactor configuration to provide a high ratio of illuminated catalyst surface area for the reduction of CO2 to fuels under visible light. The improved conversion efficiency is ascribed to the presence of the metal, Ni, which served as electrons traps that suppressed recombination, resulting in effective charge separation and CO2 reduction. More importantly, the quantum efficiency is higher than those reported in the literature that used similar reactor configurations. [Copyright &y& Elsevier]

Abstract: Anthropogenic activities are causing an increase in greenhouse gases in the atmosphere, with carbon dioxide (CO2) being the key cause of global warming. The conversion of CO2 into valuable hydrocarbons serves as a promising route for mitigating the effects of global warming and meeting future energy demands. Herein, we show the comparison between the photocatalytic reduction of CO2 for metal coated TiO2 nanoparticles in a slurry batch annular reactor system and metal coated TiO2 monoliths in an internally illuminated photoreactor system using the 1wt% Pd/0.01wt% Rh-TiO2 catalyst. Carbon based fuels, such as methane, methanol or acetaldehyde were produced in the gas phase from the CO2 reduction with water by titania nanoparticles modified by Pd and Rh for improved reactivity. The modified photocatalysts synthesized by the improved sol–gel method were tested under UV light irradiation. The quantum efficiency of the internally illuminated monolith reactor was near one order of magnitude higher than the slurry batch annular reactor. This efficiency was due to the reactor''s flexible configuration; which allows maximum exploitation of the combined advantages of the high surface area of the monolith and the elimination of uneven light distribution via the optical fibres. [Copyright &y& Elsevier]

Abstract: A family of Cu/TiO2 catalysts was prepared using a refined sol–gel method, and tested in the photocatalytic reduction of CO2 by H2O to CH4 using a stirred batch, annular reactor. The resulting photoactivity was benchmarked against pure TiO2 nanoparticles (synthesised by an identical sol–gel route). CO2 photoreduction exhibited a strong volcano dependence on Cu loading, reflecting the transition from 2-dimensional CuOx nanostructures to 3-dimensional crystallites, with optimum CH4 production observed for 0.03wt.% Cu/TiO2. [Copyright &y& Elsevier]

Pavlova microalga was pyrolysed in presence of titania based catalysts in a fixed bed reactor at various temperatures. The effects of catalysts on Pavlova microalga pyrolysis were investigated. A large fraction of the starting energy (∼ 63–74% daf) was recovered in the bio-oils when the catalysts were used. The bio-oil yield was 20% higher in presence of Ni/TiO 2 (22.55 wt%) at 500 °C. The High Heating Values of the produced bio-oils were in the range of ∼ 35–37 MJ/kg and suffered strong deoxygenation, with O content (% daf) diminished from 51 wt% to ∼ 9–12 wt%. The 1 H Nuclear Magnetic Resounance and Gas Chromatography Mass Spectrometry suggested that the titania catalysts enlarged the aliphatics and aromatic compounds and decreased oxygenates in the bio-oils. Ni/TiO 2 had the greatest activity in increasing aliphatic protons (60%) and decreasing coke formation. Its enhanced cracking activity was due to its higher availability on the catalyst surface, compared to Co and Ce, and to strong interaction between Ni and TiO 2 support. Despite the fact that the bio-oils were partially de-nitrogenated, the N-content still represent a major limitation for their use as bio-fuels without further upgrading. [ABSTRACT FROM AUTHOR]

Rechargeable zinc-air batteries (RZABs) have been described as one of the most viable next-generation battery technologies, especially due to their low cost, high capacity, and being environmental-friendly. In this work, hausmannite Mn 3 O 4 nanoparticles, obtained from low-cost commercial electrolytic manganese dioxide, were dispersed on conductive multiwalled carbon nanotubes (CNTs) and carbon nanofibers (CNFs) and investigated for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in an alkaline medium and then applied in RZAB cell. The high performance of the CNFs (in terms of electron transfer kinetics) over the CNTs has been associated with its inherent defects and nitrogen content. Density functional theory (DFT) calculations predict that CNF give higher partial density of states (PDOS, i.e., 67 eV vs 51 eV for CNT) and can allow for a more favorable distribution of the d-electrons of the Mn and enhanced synergistic effect with Mn 3 O 4 for weaker adsorption energies and p-band centers of the oxygen intermediates (O*, OH*, and OOH*). In a proof-of-concept, Mn 3 O 4 + CNF was investigated as the air cathode for RZAB in a micro-3D-printed cell configuration. The RZAB showed good performance in terms of open circuit voltage (OCV = 1.77 V), areal-discharge energy (≥40 mW h/cm 2 geometric ) and cycling stability (∼25 cycles at 8 h per cycle for 140 h at 10 mA cm -2; and ∼17 cycles at 16 h per cycle for 270 h at 5 mA cm -2 ) better than 100 catalysts used in RZAB cells in recent articles including the state-of-the-art Pt/C-IrO 2 catalysts. The findings here provide fresh physicochemical perspectives on the future design and utility of CNFs for developing Mn-based RZABs that meet or even outperform the new literature-recommended benchmark areal-discharge energy density of 35 mW h/cm 2 geometric at 10 mA cm -2 current loading for any possible application in real devices., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Photocatalysis provides an attractive approach to convert CO 2 into valuable fuels, which relies on a well-designed photocatalyst with good selectivity and high CO 2 reduction ability. Herein, a series of P25/Bi 2 WO 6 nanocomposites were synthesized by a simple one-step in situ hydrothermal method. The formation of a heterojunction between Bi 2 WO 6 , which absorbs visible light, and P25, which absorbs ultraviolet light, expands the utilization of sunlight by the catalysts, and consequently, leads to a remarkably enhanced CO 2 selective photoreduction to CO. The maximum CO yield of the P25/Bi 2 WO 6 heterojunction under simulated solar irradiation was 15.815 μmol g -1 h -1 , which was 4.04 and 2.80 times higher than that of pure P25 and Bi 2 WO 6 , respectively. Our investigations verified a Z-scheme charge migration mechanism based on various characterization techniques between P25 and Bi 2 WO 6 . Furthermore, in situ DRIFTS uncovered the related reaction intermediates and CO 2 photoreduction mechanism. Our work sheds light on investigating the efficacious construction of Bi 2 WO 6 -based hybrids for light-driven photocatalysis., Competing Interests: The authors have no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

Development of a low cost, high activity, and stable nonprecious metal bifunctional catalyst for electrocatalytic water cracking is a hot topic and big challenge. In this paper, we prepared a nitrogen-doped carbon nanotube (NCNT)-enhanced three-dimensional self-supported electrocatalyst with CoP and Co 2 P coexistence by a two-step strategy of high-temperature carbonization and low-temperature phosphorylation. Furthermore, the induced three-dimensional carbon network skeleton facilitates rapid charge transfer. In addition, the active sites of the carbon foam (CF) are greatly increased by the construction of hollow structures. As a bifunctional electrocatalyst, CoP/Co 2 P/NCNT@CF exhibited excellent catalytic activity for both hydrogen evolution reaction and oxygen evolution reaction in alkaline media, requiring low overpotentials of 133 and 289 mV to obtain a current density of 10 mA cm -2 , respectively. Additionally, the synthesized catalysts also exhibit good long-term stability, maintaining high catalytic activity after 20 h of continuous operation. We also confirmed the main driving force to improve the electron transfer between the heterostructures of Co and P by XPS spectra. The excellent electrocatalytic performance can be attributed to the close synergy between the highly active CoP/Co 2 P/NCNT and CF. This study provides a new strategy for the design of highly active bifunctional self-supporting electrocatalysts., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)