Search

In response to the global energy crisis and damage to humans by environmental issues, metal oxide nanomaterials (nonprecious) represent an important class of materials for energy conversion and environmental detection on account of their natural abundance, easy synthesis, low cost, and excellent stability. A majority of pristine metal oxide nanomaterials have certain shortcomings in catalysis and sensing, such as poor conductivity and wide bandgap. Fortunately, the regulation of the intrinsic physicochemical properties of metal oxide nanomaterials is a very promising approach for improving their catalytic and sensing properties for energy conversion and environmental detection. In this review, we will mainly discuss the regulation of the intrinsic physicochemical properties, namely, shape and size, defects, crystal facets, and ion cycles of metal oxide nanomaterials, with a majority of applications involving photocatalytic water splitting and CO2 reduction, electrocatalytic water splitting, heavy metal ion (HMI) detection, and metal oxide gas sensors. Density functional theory (DFT) calculations and X-ray absorption fine-structure (XAFS) spectroscopy analysis have been used to evaluate the effects of regulation of the intrinsic physicochemical properties of metal oxide nanomaterials, as well as to further identify the relationship between the intrinsic physicochemical properties and their enhanced catalytic and sensing properties with regard to energy conversion and environmental detection. Finally, some unresolved problems associated with future perspectives in this field are discussed, inspiring further development of the intrinsic physicochemical properties of metal oxide nanomaterials.

Nitric oxide (NO) and nitrite are of significant importance in clinical/biomedical research and in quality control applications for the food industry. Electrochemical sensing of NO and nitrite has been extensively pursued over the last two years. Efficient interfaces based on functional nanomaterials and bioactive molecules (e.g. metals, metal oxides, carbon-based nanomaterials, conducting polymers, and heme proteins) have been widely explored toward sensor development. Herein, we review the most recent advances in the electrochemical sensing of NO and nitrite, while the critical roles of nanomaterials in the design of advanced electrochemical sensors are highlighted.

The electrochemical method for highly sensitive determination of arsenic(III) in real water samples with noble-metal-free nanomaterials is still a difficult but significant task. Here, an electrochemical sensor driven by noble-metal-free layered porous Fe3O4/Co3S4 nanosheets was successfully employed for As(III) analysis, which was prepared via a facile two-step method involves a hydrothermal treatment and a subsequent sulfurization process. As expected, the electrochemical detection of As(III) in 0.1 M HAc-NaAc (pH 6.0) by square wave anodic stripping voltammetry (SWASV) with a considerable sensitivity of 4.359 μA/μg·L−1 was obtained, which is better than the commonly used noble metals modified electrodes. Experimental and characterization results elucidate the enhancement of As(III) electrochemical performance could be attributed to its nano-porous structure, the presence of oxygen vacancies and strong synergetic coupling effects between Fe3O4 and Co3S4 species. Besides, the Fe3O4/Co3S4 modified screen printed carbon electrode (Fe3O4/Co3S4-SPCE) shows remarkable stability and repeatability, valuable anti-interference ability and could be used for detection in real water samples. Consequently, the results confirm that as-prepared porous Fe3O4/Co3S4 nanosheets is identified as a promising modifier to detect As(III) in real sample analysis.

Gold-based nanomaterials have received increasing attention in a wide range of energy, environmental and medical applications due to their unique physicochemical properties, chemical robustness, and distinct catalytic activities [1-5]. In this presentation, we mainly focus on the synthesis and modification of nanoporous Au as well as its promising energy, environmental and biological applications. The primary strategies for the fabrication of nanoporous gold, including chemical dealloying, electrochemical alloying/dealloying, and dynamic hydrogen bubble template approach, will be presented. The development of nanoporous gold based electrochemical sensors for the detection of biomarkers, contaminants, and food additives will be highlighted. In addition, the high catalytic activity of nanoporous gold towards the electrochemical reduction of carbon dioxide will be discussed. References [1] Z. Liu, A. Nemec-Bakk, N. Khaper, A. Chen, Anal. Chem. 89 (2017) 8036-8043 [2] V.S. Manikandan, B.-R. Adhikari, A. Chen, Analyst 143 (2018) 4537-4554 [3] M.N. Hossain, Z. Liu, J. Wen, A. Chen, Appl. Catal. B: Environ. 236 (2018) 483-489 [4] Z. Liu, V.S. Manikandan, A. Chen, Current Opin. Electrochem. 16 (2019) 127-133 [5] Z. Liu, E. Puumala, A. Chen, Sens. Actuators B: Chem. 287 (2019) 517-525.