Wearable electronics represent a significant paradigm shift in consumer electronics since they eliminate the necessity for separate carriage of devices. In particular, integration of flexible electronic devices with clothes, glasses, watches, and skin will bring new opportunities beyond what can be imagined by current inflexible counterparts. Although considerable progresses have been seen for wearable electronics, lithium rechargeable batteries, the power sources of the devices, do not keep pace with such progresses due to tenuous mechanical stabilities, causing them to remain as the limiting elements in the entire technology. Herein, we revisit the key components of the battery (current collector, binder, and separator) and replace them with the materials that support robust mechanical endurance of the battery. The final full-cells in the forms of clothes and watchstraps exhibited comparable electrochemical performance to those of conventional metal foil-based cells even under severe folding-unfolding motions simulating actual wearing conditions. Furthermore, the wearable textile battery was integrated with flexible and lightweight solar cells on the battery pouch to enable convenient solar-charging capabilities.

Realization of sensing multidirectional strains is essential to understanding the nature of complex motions. Traditional uniaxial strain sensors lack the capability to detect motions working in different directions, limiting their applications in unconventional sensing technology areas, like sophisticated human-machine interface and real-time monitoring of dynamic body movements. Herein, a stretchable multidirectional strain sensor is developed using highly aligned, anisotropic carbon nanofiber (ACNF) films via a facile, low-cost, and scalable electrospinning approach. The fabricated strain sensor exhibits semitransparency, good stretchability of over 30%, outstanding durability for over 2500 cycles, and remarkable anisotropic strain sensing performance with maximum gauge factors of 180 and 0.3 for loads applied parallel and perpendicular to fiber alignment, respectively. Cross-plied ACNF strain sensors are fabricated by orthogonally stacking two singlelayer ACNFs, which present a unique capability to distinguish the directions and magnitudes of strains with a remarkable selectivity of 3.84, highest among all stretchable multidirectional strain sensors reported so far. Their unconventional applications are demonstrated by detecting multi-degrees-offreedom synovial joint movements of the human body and monitoring wrist movements for systematic improvement of golf performance. The potential applications of novel multidirectional sensors reported here may shed new light into future development of next-generation soft, flexible electronics.To satisfy the growing interests, significant efforts have been made to improve their overall performances. Various materials and structures, [14][15][16][17][18] including nanosize metals, [19][20][21][22] conductive polymers, [23][24][25] nanocarbon materials, [26][27][28][29][30] and fiber or core-shell structure, [14,16,31] have been utilized to enhance the sensitivity, stretchability, linearity, and stability. Unfortunately, however, these strain sensors are designed to mainly detect a uniaxial strain while sensing multidirectional strains has rarely been accomplished, restricting their widespread applications. [32,33] The difficulty in achieving multidirectional strain sensing is due to the macro-or microscopically isotropic nature of conducting networks of strain sensors, which usually experience similar deformation upon stretching in any direction. To address this issue, geometrically engineered flexible strain gauge rosettes [34] and cross-shaped strain sensors [35] composed of isotropic piezoresistive materials were introduced previously. However, they showed a limited success with a small sensing range and an insufficient capability to distinguish the changes in multiaxial strain conditions because the isotropic piezoresistive materials experience significant destruction in their networks at high strains, regardless of the loading directions. To measure complex motions in 3D space with high accuracy requires rational design and use of suitable materials capable of detect...

The insufficient strategies to improve electronic transport, the poor intrinsic chemical activities, and limited active site densities are all factors inhibiting MXenes from their electrocatalytic applications in terms of hydrogen production. Herein, these limitations are overcome by tunable interfacial chemical doping with a nonmetallic electron donor, i.e., phosphorization through simple heattreatment with triphenyl phosphine (TPP) as a phosphorous source in 2D vanadium carbide MXene. Through this process, substitution, and/or doping of phosphorous occurs at the basal plane with controllable chemical compositions (3.83-4.84 at%). Density functional theory (DFT) calculations demonstrate that the PC bonding shows the lowest surface formation energy (ΔG Surf ) of 0.027 eV Å −2 and Gibbs free energy (ΔG H ) of -0.02 eV, whereas others such as P-oxide and PV (phosphide) show highly positive ΔG H . The P3-V 2 CT x treated at 500 °C shows the highest concentration of PC bonds, and exhibits the lowest onset overpotential of -28 mV, Tafel slope of 74 mV dec −1 , and the smallest overpotential of −163 mV at 10 mA cm −2 in 0.5 m H 2 SO 4 . The first strategy for electrocatalytically accelerating hydrogen evolution activity of V 2 CT x MXene by simple interfacial doping will open the possibility of manipulating the catalytic performance of various MXenes.

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Long‐lived afterglow emissions, such as room‐temperature phosphorescence (RTP) and thermally activated delayed fluorescence (TADF), are beneficial in the fields of displays, bioimaging, and data security. However, it is challenging to realize a single material that simultaneously exhibits both RTP and TADF properties with their relative strengths varied in a controlled manner. Herein, a new design approach is reported to control singlet–triplet energy splitting (∆EST) in graphene quantum dots (GQD)/graphene oxide quantum dots (GOQDs) by varying the ratio of oxygenated carbon to sp2 carbon (γOC). It is demonstrated that ∆EST decreases from 0.365 to 0.123 eV as γOC increases from 4.63% to 59.6%, which in turn induces a dramatic transition from RTP to TADF. Matrix‐assisted stabilization of triplet excited states provides ultralong lifetimes to both RTP and TADF. Embedded in boron oxynitride, the low oxidized (4.63%) GQD exhibits an RTP lifetime (τTavg) of 783 ms, and the highly oxidized (59.6%) GOQD exhibits a TADF lifetime (τDFavg) of 125 ms. Furthermore, the long‐lived RTP and TADF materials enable the first demonstration of anticounterfeiting and multilevel information security using GQD. These results will open up a new approach to the engineering of singlet–triplet splitting in GQD for controlled realization of smart multimodal afterglow materials.

In the search for the formation of Frank–Kasper phases from diblock copolymer self‐assembly, a series of compositionally asymmetric poly(dimethylsiloxane)‐b‐poly(2,2,2‐triflouroethyl acrylate)s (PDMS‐b‐PTFEAs) are synthesized to produce PDMS‐rich phases with PDMS volume fractions (fPDMS) ranging from 0.746 to 0.869. As determined by small‐angle X‐ray scattering analysis, the Frank–Kasper σ and C14 phases are identified at fPDMS = 0.796 and 0.851, respectively, plausibly due to high conformational asymmetry (ε ≈ 2.20) between the two blocks. Intriguingly, the σ phase develops during heating from a short‐range liquid‐like packing (LLP) state, whereas the C14 phase is achieved at room temperature, which are both followed by a disordering at higher temperatures. Based on thermal experiments from a super cooled disordered state, the findings further provide compelling evidence of an LLP‐hexagonally packed cylinder‐σ transition and a direct pathway to the C14 phase during heating from an LLP state.

Z-scheme in natural photosynthesis are promising for solar-driven CO 2 conversion. [2] By combining multiple photoelectrodes or photovoltaics (PV), the Z-scheme PEC cells can provide sufficient photopotential to simultaneously drive water oxidation and CO 2 reduction under minimal or no external bias. [3] Nevertheless, lowering the kinetic barrier of thermodynamically inert CO 2 remains a hurdle for efficient CO 2 reduction. The development of CO 2reducing biocatalyst-conjugated cathodes can improve chemoselectivity and increase yield under mild conditions. [4] Compared to synthetic catalysts that often require extreme conditions such as high pressure, pH, or temperature, enzymes show high catalytic activities and specificities under mild conditions, making them a valuable catalyst for sustainable and green applications. In particular, formate dehydrogenase (FDH) is an attractive redox enzyme that reduces CO 2 to formate, an alternative water-soluble feedstock that can be easily converted to other common fuels. [5] Previous studies have focused on mediated electron transfer (MET)-type reactions, [6] in which redox mediators such as nicotinamide adenine dinucleotide cofactor (NADH) and Rh-based complexes shuttle electrons between an electrode and FDH. However, the MET-based biocatalysis requires costly electron mediators and multiple electron transfer steps that cause side reactions and significant losses in efficiency. [7] Here, we report the development of 3D titanium nitride nanoshell (3D TiN) electrodes for biocatalytic PEC cells that convert CO 2 to formate through direct electron transfer (DET), as depicted in Scheme 1a. A highly ordered, porous TiN structure is employed as an electrically conductive scaffold for efficient DET to a W-containing FDH from Clostridium ljungdahlii (ClFDH) (inset, Scheme 1a). TiN was chosen as a scaffold for DET-based bioelectrode because it is highly conductive, electrochemically stable and exhibit high chemical and thermal resistance, as well as exceptional hardness. [8] The 3D TiN electrode simultaneously provides (i) a large electroactive surface area generated from an ultrathin (≈30 nm), 3D nanoshell structure with high porosity (92.1%) for high enzyme loading per geometric area, (ii) a continuous electron transfer network with high electrical Z-scheme-inspired tandem photoelectrochemical (PEC) cells have received attention as a sustainable platform for solar-driven CO 2 reduction. Here, continuously 3D-structured, electrically conductive titanium nitride nanoshells (3D TiN) for biocatalytic CO 2 -to-formate conversion in a bias-free tandem PEC system are reported. The 3D TiN exhibits a periodically porous network with high porosity (92.1%) and conductivity (6.72 × 10 4 S m −1 ), which allows for high enzyme loading and direct electron transfer (DET) to the immobilized enzyme. It is found that the W-containing formate dehydrogenase from Clostridium ljungdahlii (ClFDH) on the 3D TiN nanoshell is electrically activated through DET for CO 2 reduction. At a low overpotential...