Photochemical Construction of Nitrogen-Containing Nanocarbons for Carbon Dioxide Photoreduction

Advances in sustainable nano-biochar: precursors, synthesis methods and applications

Nano-biochar, characterized by its environmentally friendly nature and unique nanostructure, offers a promising avenue for sustainable carbon materials. With its small particle size, large specific surface area, abundant functional groups and tunable pore structure, nano-biochar stands out due to its distinct physical and chemical properties compared to conventional biochar. This paper aims to provide an in-depth exploration of nano-biochar, covering its sources, transformation mechanisms, properties, applications, and areas requiring further research. The discussion begins with an overview of biomass sources for nano-biochar production and the conversion processes involved. Subsequently, primary synthesis methods and strategies for functionalization enhancement are examined. Furthermore, the applications of nano-biochar in catalysis, energy storage, and pollutant adsorption and degradation are explored and enhanced in various fields.

Integrating Co(OH)2 nanosheet arrays on graphene for efficient noble-metal-free EY-sensitized photocatalytic H2 evolution

The development of an efficient noble-metal-free cocatalyst is the key to photocatalytic hydrogen production technology. In this study, hierarchical Co(OH)2 nanosheet array-graphene (GR) composite cocatalysts are developed. With Eosin Y (EY) as a photosensitizer, the optimal Co(OH)2-10%GR hybrid cocatalyst presents excellent photocatalytic activity with an H2 production rate of 17 539 μmol g-1 h-1, and the apparent quantum yield for hydrogen production can reach 12.8% at 520 nm, which remarkably surpasses that of pure Co(OH)2 and most similar hybrid cocatalyst systems. Experimental investigations demonstrate that the excellent photocatalytic activity of Co(OH)2-GR arises from its unique nanosheet array architecture, which can collaboratively expose rich active sites for photocatalytic hydrogen evolution and facilitate the migration and separation of photogenerated charge carriers. It is desired that this study would supply a meaningful direction for the rational optimization of the constitute and structure of cocatalysts to achieve efficient photocatalytic hydrogen generation.

Research status, challenges and future prospects of renewable synthetic fuel catalysts for CO2 photocatalytic reduction conversion

In recent years, with global climate change, the utilization of carbon dioxide as a resource has become an important goal of human society to achieve carbon peaking and carbon neutrality. Among them, the catalytic conversion of carbon dioxide to generate renewable fuels has received great attention. As one of these methods, photocatalysis has its unique properties and mechanism, which can only rely on sunlight without inputting other energy. It is an emerging discipline with great development prospects. The core of photocatalysis lies in the development of photocatalysts with high activity, high selectivity, low cost, and high durability. This review first introduces the background and mechanism of photocatalysis, then introduces various types of photocatalysts based on different substrates, and analyzes the methods and mechanisms to improve the activity and selectivity of photocatalysts. Finally, combining the plasmon effect with photocatalysis, the review analyzes the promoting effect of the plasmon effect on the photocatalytic carbon dioxide synthesis of renewable fuels, which provides a new idea for it.

Optimization of Fe/Ni organic frameworks with core-shell structures for efficient visible-light-driven reduction of carbon dioxide to carbon monoxide

To address CO₂ emissions caused by the overuse of fossil fuels, photocatalytic CO₂ reduction from metal-organic frameworks (MOFs) to valuable chemicals is critical for energy conversion and storage. Core-shell MOFs improve interfacial interactions, increasing the number of active sites in the catalyst, thereby improving the photocatalytic reduction. In this work, the catalytic performance of Fe/Ni-MOFs toward photocatalytic CO₂ reduction was improved using a bimetallic strategy. We successfully synthesized a series of Fe/Ni-MOFs with a core-shell structure using a single-step approach combined with hydrothermal synthesis. By altering the synthesis conditions of the bimetallic organic skeleton and contrasting it with a single MOF, we successfully synthesized Fe/Ni-T120 through an efficient photocatalytic reduction of CO₂. The results of photocatalytic CO₂ reduction experiments indicated that upon using [Ru(bpy)₃]Cl₂·6H₂O as a photosensitizer and triethanolamine (TEOA) and acetonitrile (MeCN) as sacrificial agents, the CO evolution rate of Fe/Ni-T120 reached 9.74 mmol g^-1 h^-1 and the CO₂ to CO selectivity reached up to 92.1%. Additionally, Fe/Ni-T120 has a broad response range to visible light, a high photocurrent intensity, good chemical stability, and strong photocatalytic efficiency, even after repeated cycles. This study proposes a straightforward method for producing adaptable and stable MOFs for effective photocatalytic CO₂ reduction that is driven by visible light.

Light-Induced Synthesis of Oxygen-Vacancy-Functionalized Ni(OH)2 Nanosheets for Highly Selective CO2 Reduction

Solar-driven CO₂ reduction into fuels and chemicals has gained increasing attention in recent years. In this study, oxygen-vacancies-functionalized Ni(OH)₂ (OVs-Ni(OH)₂ ) nanosheets are synthesized by a photochemical method to serve as a catalyst for CO₂ reduction. Characterization reveals that COOH* is the key intermediate for CO₂ -to-CO photoreduction. Experimental results and theoretical calculations confirm that OVs modification can greatly modulate the interaction strength between the OVs-Ni(OH)₂ and CO₂ , while lowering the energy barrier for COOH* formation, thereby preferentially facilitating CO₂ reduction. As a result, the OVs-Ni(OH)₂ catalyst exhibits outstanding activity and selectivity for CO₂ -to-CO photoreduction with visible light. A CO evolution rate of 31.58 μmol h^-1 (0.35 mg catalyst, 90228 μmol h^-1  g^-1 ) with a selectivity of 98 % over OVs-Ni(OH)₂ was achieved, outperforming most analogous reported catalysts. Moreover, even under a low CO₂ concentration of 0.04 % (representative of the CO₂ concentration in air) and low reaction temperature (273 K, 0 °C), this catalyst can still trigger CO₂ reduction. This work provides a new method to synthesize OVs-Ni(OH)₂ catalysts for efficient CO₂ reduction and establishes a relationship between the OVs and the catalytic activity, which may guide the design of highly selective CO₂ reduction catalysts.

Role of carbon quantum dots on Nickel titanate to promote water oxidation reaction under visible light illumination

Water oxidation reaction (WOR) is the heart for overall water splitting owing to its sluggish kinetics. Herein, carbon quantum dots (CQDs) are studied as co-catalyst to promote WOR by loading them on NiTiO₃ (NTO) photocatalyst. The performance can be obtained in a fold of 7 compared with pristine NTO in power-based photocatalytic system, and strong stability has received with preserving the output for at least 10 h. The CQDs have also demonstrated to load on NTO based photoanode for WOR, and a 6 times increasement has realized. In-situ characterizations have acquired to study the roles of CQDs for WOR and found that CQDs can facilitate the chemical adsorption of water molecules, and meanwhile promote the formation of hydroxyl radical as transition states of WOR. This demonstration presents a clue to understand the role of carbon in photocatalytic system to promote WOR and encourage its uses for advanced photoredox catalytic reactions.