Defects in crystalline nanozymes play a critical role in enhancing their performances and related catalytic events. However, creating a high concentration of active and robust defects in well-explored crystalline metal oxides to achieve high-performance single-enzymatic activity is challenging. Herein, amorphous BiVO4 beyond traditional crystalline nanozymes is prepared via a facile solution-processed coprecipitation method favorable to large-scale manufacturing to mimic enzymatic properties. As expected, the specially designed amorphous material without any post-treatments has sufficient and robust oxygen vacancies, which are highly active in converting oxygen to reactive radicals (O2 –•). Simultaneously, the negatively charged surface has a high affinity for the substrate, facilitating charge transfer between materials and substrates and, in turn, providing higher catalytic efficiency compared to the crystalline counterparts. Most importantly, the sample can only mimic oxidase-like activity rather than the multienzyme-like activity generally observed in most reported crystalline metal oxides, which is a step forward in the development of nanozymes. This amorphous BiVO4-based system is also evaluated for the sensitive and selective detection of l-cysteine. The study provides insight into nanozyme development and highlights the great potential of amorphous materials in addition to amorphous BiVO4.

A simple method for measuring grating groove density as well as its position and orientation is proposed based on the idea of ERT (Experimental Ray Tracing). Conventional methods only measure grating groove density with accuracy limited by its rotary stage and goniometer. The method proposed in the paper utilizes linear guides which could be calibrated to much higher accuracy. It is applicable to gratings of arbitrary surface profile or mosaic of a group of various gratings. Various measurement error sources are simulated by the Monte Carlo method and the results show high accuracy capability of grating parameters identification. A verification testing is performed. The accuracy dependency on main configuration parameters is evaluated. A method to expand measurement range by double wavelength is also discussed.

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