Sweat pH monitoring is a routine indicator in wearable biotechnology. The state-of-the-art wearable pH sensors mostly rely on organic materials but face the risk of biological toxicity. WO 3 is a typical H + -sensitive inorganic material with chemical stability, biocompatibility, and low cost but low sensitivity and slow response. Lattice H + intercalation is herein proposed as an efficient approach that can greatly improve the sensitivity and selectivity of WO 3based pH sensors. Specifically, lattice H + intercalation can promote WO 3 from the monoclinic phase to cubic phase, which enhances the ion exchange capacity between WO 3 and H + . The resistance decreases more than two orders of magnitudes, which improves the interfacial charge transport. The occupancy of lattice H + leads to ion exchange only with H + , thus increasing the H + recognition. The intercalated H x WO 3 exhibits much improved sensitivity, reversibility, and response time. Additionally, the H x WO 3 is integrated with a solid reference electrode on a miniaturized chip for wearable sweat pH monitoring. The pH sensor exhibits good potential response even at curving over 270°. On-body sweat pH measurments show high accuracy compared with ex situ analyses. This work emphasizes the concept of lattice proton intercalation to regulate the H + recognition of solid contacts.

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Creating nanosized pores in layered materials can increase the abundant active surface area and boost potential applications of energy storage devices. Herein, a unique synthetic strategy based on polyaniline (PANI) doped 2D cobalt-iron layered double hydroxide (CoFe-LDH/P) nanomaterials are designed, and the formation of pores at low temperature (80 °C) is developed. It is found that the optimized concentration of PANI creates the nanopores on the CoFe-LDH nanosheets among all other polymers. The well-ordered pores of CoFe-LDH/P allow the high accessibility of the redox-active sites and promote effective ion diffusion. The optimized CoFe-LDH/P2 cathode reveals a specific capacitance 1686 (1096 Cg −1 ) and 1200 Fg −1 (720 Cg −1 ) at 1 and 30 Ag −1 respectively, a high rate capability (71.2%), and a long cycle life (98% over 10 000 cycles) for supercapacitor applications. Charge storage analysis suggests that the CoFe-LDH/P2 electrode displays a capacitive-type storage mechanism (69% capacitive at 1 mV s −1 ). Moreover, an asymmetric aqueous supercapacitor (CoFe-LDH/P2//AC) is fabricated, delivering excellent energy density (75.9 Wh kg −1 at 1124 W kg −1 ) with outstanding stability (97.5%) over 10 000 cycles. This work opens a new avenue for designing porous 2D materials at low temperature for aqueous energy storage devices.

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