Surface Defect and Wettability Engineering of Porous SnOx for Reliable Bioassays with High Selectivity and Wide Linear Dynamic Range.

Bioassay systems that can selectively detect biomarkers at both high and low levels are of great importance for clinical diagnosis. In this work, we report an enzyme electrode with an oxygen reduction reaction (ORR)-tolerant H2O2 reduction property and an air-liquid-solid triphase interface microenvironment by regulating the surface defects and wettability of nanoporous tin oxide (SnOx). The enzyme electrode allows the oxygen that is required for the oxidase catalytic reaction to be transported from the air phase to the reaction zone, which greatly enhances the enzymatic kinetics and increases the linear detection upper limit. Meanwhile, the ORR-tolerant H2O2 reduction property of SnOx catalysts achieved via oxygen vacancy engineering greatly reduces the interferent signals caused by oxygen and various easily oxidizable endogenous/exogenous species, which enables the selective detection of biomarkers at trace levels. The synergistic effect between these two novel qualities features a bioassay system with a wide dynamic linear range and high selectivity for the accurate detection of a wide range of biomarkers, such as glucose, lactic acid, uric acid, and galactose, offering the potential for reliable clinical diagnosis applications.

Cobalt-Promoted Noble-Metal Catalysts for Efficient Hydrogen Generation from Ammonia Borane Hydrolysis.

Ammonia borane (AB) has been regarded as a promising material for chemical hydrogen storage. However, the development of efficient, cost-effective, and stable catalysts for H2 generation from AB hydrolysis remains a bottleneck for realizing its practical application. Herein, a step-by-step reduction strategy has been developed to synthesize a series of bimetallic species with small sizes and high dispersions onto various metal oxide supports. Superior to other non-noble metal species, the introduction of Co species can remarkably and universally promote the catalytic activity of various noble metals (e.g., Pt, Rh, Ru, and Pd) in AB hydrolysis reactions. The optimized Pt0.1%Co3%/TiO2 catalyst exhibits a superhigh H2 generation rate from AB hydrolysis, showing a turnover frequency (TOF) value of 2250 molH2 molPt-1 min-1 at 298 K. Such a TOF value is about 10 and 15 times higher than that of the monometal Pt/TiO2 and commercial Pt/C catalysts, respectively. The density functional theory (DFT) calculation reveals that the synergy between Pt and CoO species can remarkably promote the chemisorption and dissociation of water molecules, accelerating the H2 evolution from AB hydrolysis. Significantly, the representative Pt0.25%Co3%/TiO2 catalyst exhibits excellent stability, achieving a record-high turnover number of up to 215,236 at room temperature. The excellent catalytic performance, superior stability, and low cost of the designed catalysts create new prospects for their practical application in chemical hydrogen storage.