Boosted electrocatalytic activity of nitrogen-doped porous carbon triggered by oxygen functional groups

A One-Step Self-Flowering Method toward Programmable Ultrathin Porous Carbon-Based Materials for Microwave Absorption and Hydrogen Evolution

Ultrathin 2D porous carbon-based materials offer numerous fascinating electrical, catalytic, and mechanical properties, which hold great promise in various applications. However, it remains a formidable challenge to fabricate these materials with tunable morphology and composition by a simple synthesis strategy. Here, a facile one-step self-flowering method without purification and harsh conditions is reported for large-scale fabrication of high-quality ultrathin (≈1.5 nm) N-doped porous carbon nanosheets (NPC) and their composites. It is demonstrated that the layered tannic/oxamide (TA/oxamide) hybrid is spontaneously blown, exfoliated, bloomed, in situ pore-formed, and aromatized during pyrolysis to form flower-like aggregated NPC. This universal one-step self-flowering system is compatible with various precursors to construct multiscale NPC-based composites (Ru@NPC, ZnO@NPC, MoS2 @NPC, Co@NPC, rGO@NPC, etc.). Notably, the programmable architecture enables NPC-based materials with excellent multifunctional performances, such as microwave absorption and hydrogen evolution. This work provides a facile, universal, scalable, and eco-friendly avenue to fabricate functional ultrathin porous carbon-based materials with programmability.

Insight into the amorphous nickel-iron (oxy)hydroxide catalyst for efficient oxygen evolution reaction

The specific roles of Ni and Fe in nickel-iron (oxy)hydroxide catalyst (NiFeO_x(OH)_y) are extensively discussed during oxygen evolution reaction (OER). However, there still remains controversy about whether Ni or Fe species as the dominate active site. In this work, we reported the NiFeO_x(OH)_y catalysts with varied atomic ratio of nickel and iron for OER to explore the dominate active site during OER processes. From the electrochemical performances, the similar Tafel slopes of catalysts with Fe species can achieve at a level of 40 mV dec^-1, outperforming the Tafel slopes of catalysts without Fe species. Thus, it can be concluded that the present Fe site can serve as the dominant active site in NiFeO_x(OH)_y for OER. Meanwhile, the Ni species is proved as the OH^- adsorption site, which is beneficial to the Fe site to deliver a better OER performance. As a result, the catalyst with an optimal Ni/Fe interface (atomic ratio of 1 : 1.18) displays outstanding OER performances. It only requires a low overpotential of 250 mV to deliver current density of 10 mA cm^-2 and exhibits a small Tafel slope of 39 mV dec^-1. This catalyst also shows remarkable stability with negligible potential decay after 50 h at a current density of 50 mA cm^-2. This work offers a new sight into the specific roles of Ni and Fe in NiFeO_x(OH)_y for OER.

Electrochemical Determination of Nicotine in Tobacco Products Based on Biosynthesized Gold Nanoparticles

In this work, gold nanoparticles were biosynthesized via Plectranthus amboinicus leaf extract as the reducing agent. A series of techniques were used for sample analysis. The biosynthesized gold nanoparticles (bAuNPs) are a uniform size with a spherical shape. The FTIR analysis reveals the presence of many oxygen-containing functional groups on the bAuNP surface. The cyclic voltammetry and electrochemical impedance spectroscopic characterizations reveal that while the bAuNPs have a slightly lower conductivity than chemically synthesized AuNPs (cAuNPs). However, the bAuNPs have a superior electrocatalytic performance toward nicotine reduction. After optimization, the bAuNP-modified SPE could detect nicotine linearly from 10 to 2,000 μM with a low detection limit of 2.33 μM. In addition, the bAuNPs/SPE have been successfully used for nicotine-containing-product analysis.

Morphology engineering of ZnO nanorod arrays to hierarchical nanoflowers for enhanced photocatalytic activity and antibacterial action against Escherichia coli

A facile, efficient hydrothermal synthesis of ZnO nanoflowers followed by post-synthetic annealing and their photocatalytic and antibacterial properties are reported.

Interfaces of graphitic carbon nitride-based composite photocatalysts

This review concentrates on the interface issues of g-C₃N₄-based photocatalysts, including methods for constructing interfaces, techniques for identifying interfaces, and the types and roles of the as-developed interfaces.

A facile synthesis of a highly efficient β-Bi2O3/Bi2O2CO3 heterojunction with enhanced photocatalytic NO oxidation under visible light

Photocatalytic oxidation mechanism of NO on β-Bi₂O₃/Bi₂O₂CO₃.

Enhancement of cadmium removal by oxygen-doped carbon nitride with molybdenum and sulphur hybridization

Graphitic carbon nitride, as a popular material in the field of environmental remediation, still suffers from unsatisfactory performance for heavy metals adsorption owing to lack of specific adsorption sites. In this study, molybdenum (Mo) and sulphur (S) were simultaneously introduced onto the surface of oxygen-doped graphitic carbon nitride (OCN) for the enhancement of Cd²⁺ adsorption. The synthesized MOS/OCN-1 exhibited substantially increased maximum adsorption capacity of 293.8 mg/g, calculated from Sips isotherm model, which was 8.7 times higher than that for pristine OCN (33.9 mg/g). The adsorption efficiency of MOS/OCN-1 was >94% even under high concentration of coexisting ions (i.e., Ca²⁺, Mg²⁺ and Zn²⁺). MoO₃ and MoS₂ on the surface of OCN were proven to interact with Cd²⁺ by forming CdMoO₄ and CdS species. OCN provided a stable matrix with a large surface area making more active sites exposed, which greatly facilitated Mo(IV) oxidation and Cd²⁺ precipitation. Our findings revealed that as well as the well-known Cd-S interaction, Mo atoms in the hybrid composites also played an important role in Cd²⁺ removal, which opened up the application possibility of OCN with Mo and S hybridization for in-situ Cd²⁺ remediation.