New
methods for portable detection of arsenate are still in urgent need.
Herein, we explored a simple but sensitive thermometric strategy for
arsenate determination without complex instruments and skilled technicians.
Cobalt oxyhydroxide (CoOOH) nanoflakes, can ingeniously decompose
hydrogen peroxide into oxygen in a sealed reaction vessel, accompanied
by marked pressure and significant temperature increase due to the
exothermic reaction effect (ΔH = −98.2
kJ/mol). The increased pressure then compelled a certain amount of
H2O overflowing from the drainage device into another vessel,
leading to a significant temperature decrease due to the preloaded
ammonium nitrate (NH4NO3) and its good dissolution
endothermic effect (ΔH = 25.4 kJ/mol). In the
presence of arsenate, the catalytic activity of CoOOH nanoflakes for
H2O2 decomposition was inhibited dramatically,
resulting in an obvious decrease of the pressure, weighting water
and temperature response. The two temperature responses with increasing
and decreasing feature were easily measured through a common thermometer,
and exhibited an effective signaling amplification via coupling both
“signal-on” and “signal-off” temperature
readout elements. The obtained dual superimposing temperature readout
exhibits a good linear with the concentration of arsenate with a lower
detection limit (51 nM, 3.8 ppb). Compared to the inductively coupled
plasma mass spectrometry, this enhanced thermometric strategy provides
a simple, rapid, convenient, low cost, and portable platform for sensing
arsenate in real environmental water.