; significantly higher than those of reported adsorbents. Exceptional adsorption capacities for arsenic are retained over a wide pH range, and high selectivity for AsIJV) is realized even in the presence of co-existing anions. The arsenic adsorption performance correlates to the properties of the composites including the Mg/Al ratio, point of zero charge, crystallinity and mesostructure. The arsenic adsorption mechanism is elucidated. Due to their high surface areas, large pore volumes, tunable mesopore structures and high quantities of accessible hydroxyl groups with strong chemisorption binding affinity to arsenic, as well as extremely high adsorption capacities and selectivity, these mesoporous aluminium magnesium oxides are promising adsorbent candidates for the remediation of arsenic in water.

Synthesis of carbon nitrides (CN) by refluxing under nitrogen exhibited mixed growth mechanisms of oriented attachment and Ostwald ripening, leading to the formation of coral reef-like microstructures from spherical agglomerates. Some phase transformation from β-phase to α-phase CN occurred upon refluxing for 1.5 h, producing a biphasic CN. The N content relative to C was determined from CHN elemental analysis, and the presence of C═N and terminal groups (i.e., COOH and NH) was consistent with the Fourier transform infrared, nuclear magnetic resonance, and X-ray photoelectron spectroscopic results. The sample refluxed for 2.0 h (CN/2.0 h) had the highest surface area of 24.5 m·g and displayed enhanced adsorption capacities for methylene blue (MB) molecules and heavy metal ions Pb (720 mg·g), Cd (480 mg·g), and As(V) (220 mg·g), which was attributed to the presence of COOH functional groups. CN samples had a negative surface charge that electrostatically attracted the cationic heavy metal ions as well as MB molecules for subsequent photodecomposition under visible-light illumination. The photocatalytic activity of CN/2.0 h toward phenol, a common pollutant in aqueous waste, was also demonstrated and a possible photocatalytic route was proposed.

Titanium dioxide is widely known as a prominent photocatalyst material and research in this area has increased substantially over the last decades. However, the photoactivity of TiO2 is hindered by several factors, such as a relatively high photogenerated electron-hole recombination rate and a wide bandgap of ∼ 3.2 eV, rendering it inactive under visible light. Approaches to optimize the TiO2 photocatalyst, either by altering its morphological or chemical properties, have been conducted for many years, yet further modification of this semiconductor has the potential to yield photocatalysts with excellent properties and higher photocatalytic activity. This could be effectively explored using combinatorial synthesis coupled with high-throughput characterization approaches. Such an approach has been widely applied for the discovery of new functional materials, including photocatalysts. By using high-throughput synthesis and characterization technology, preparation and screening of materials on small sample scales can be accelerated; hence, new TiO2-based photocatalysts with enhanced photocatalytic activity can be acquired more rapidly. Additionally, the large database of materials being systematically examined will greatly build our fundamental understanding of the relation between materials structure/composition and photocatalytic activity. This review details various high-throughput syntheses and characterization techniques applied to improve the photocatalytic properties of TiO2 materials and discuss several challenges that have been raised or may be encountered in the future when using this approach.