Photocatalytic water splitting is an environmentally friendly technique for hydrogen production. In this work, we report a novel photocatalyst consisting of two-dimensional (2D) titanium carbide (Ti₂C) and graphitic carbon nitride (g-C₃N₄). We observe substantially enhanced water splitting activities due to the efficient synergistic interaction between Ti₂C and g-C₃N₄. Optimal properties are achieved in the g-C₃N₄ with a loading of 0.4 wt% Ti₂C with a hydrogen production rate of 47.5 μmol h⁻¹, which is 14.4 times as much as that in the case using pure g-C₃N₄, and it even outperforms Pt-loaded g-C₃N₄. We further show that the Ti₂C/g-C₃N₄ has high stability and good reproducibility. We expect that the Ti₂C/g-C₃N₄ can be a photocatalyst for large scale applications because both Ti₂C and g-C₃N₄ are low-cost, abundant, and nontoxic.

Synergistic effect of 2D Ti₂C and g-C₃N₄ for efficient photocatalytic hydrogen production

2D metal carbides and nitrides (MXenes) for sensors and biosensors.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9605918

Towards hospital-on-chip supported by 2D MXenes-based 5th generation intelligent biosensors

MOF-derived Ni-Co bimetal/porous carbon composites as electromagnetic wave absorber

Paper-supported near-infrared-light-triggered photoelectrochemical platform for monitoring Escherichia coli O157:H7 based on silver nanoparticles-sensitized-upconversion nanophosphors.

A dual-model “on-super off” photoelectrochemical/ratiometric electrochemical biosensor for ultrasensitive and accurate detection of microRNA-224

Two-dimensional (2D) materials with unique structures and fascinating photoelectric properties are typically employed as supporting materials but they have not been mentioned in the context of polarity-reversal-mode photoelectrochemical (PEC) biosensors. Herein, a novel 2D Ti2C MXene-induced photocurrent polarity switching PEC biosensing platform was constructed for the selective and ultrasensitive detection of soluble CD146 (sCD146). Ag2S quantum dots (QDs)-fixed indium-tin oxide slices were used as the photocathode electrodes, and the capture antibody (Ab1) was assembled on the electrode. When the target sCD146 existed, 2D Ti2C MXene labeled with the detection antibody (Ab2) was introduced onto the modified electrode through a typical antigen-antibody sandwich immune reaction, resulting in a polarity switch from a cathodic to an anodic photocurrent. The outstanding optical and electron-transfer capability of the 2D Ti2C MXene made it beneficial to establish a high-performance photocurrent polarity switching PEC biosensor for sCD146 assay, and a linear response range of 0.1–1000 pg/mL with a detection limit of 18 fg/mL was obtained. Furthermore, the developed PEC biosensing strategy possessed excellent anti-interference ability for precluding the false positive or negative signals. The designed 2D Ti2C MXene opens up a new two-dimensional photocurrent-polarity switcher for constructing high-performance PEC biosensors, and the environmentally friendly 2D Ti2C MXene//Ag2S QDs photocurrent polarity switching system could overcome the harmfulness of conventional toxic semiconductors for operators and the environment, offering great potential applications in biological analysis and disease diagnosis.

Two-dimensional Ti2C MXene-induced photocurrent polarity switching photoelectrochemical biosensing platform for ultrasensitive and selective detection of soluble CD146

Amorphous carbon engineering of hierarchical carbonaceous nanocomposites toward boosted dielectric polarization for electromagnetic wave absorption

Herein, the multifunctional carbon nanodots (CDs)-decorated plasmonic [email protected] nanoenzymes coupled with Ti2C/Ag2S composites were proposed for photoelectrochemical (PEC) biosensing of microRNA. Two-dimensional (2D) Ti2C MXenes-sensitized Ag2S quantum dots (QDs) (Ti2C/Ag2S composites) acquired an initial photocurrent. After immobilization of a hairpin subsidiary probe (S1) onto the Ti2C/Ag2S composites photoelectrode surface, the target microRNA-associated bipedal DNA walker performed the opening of S1 for forming triple helix molecules. Then the CDs-decorated [email protected] core–shell ([email protected]@CDs) nanocuboids were introduced into the PEC biosensing platform through target-induced triple helix molecules. The [email protected]@CDs nanocuboids as a multifunctional signal amplifier not only competitively captured the irradiating light and electron donors to weaken the PEC signal, but also quenched the photocurrent response resulting from energy transfer between plasmonic bimetallic [email protected] nanocuboids and Ag2S QDs. Additionally, the [email protected] and CDs in [email protected]@CDs nanocuboids displayed a synergistic catalytic effect, and could serve as peroxidase nanoenzymes to catalyze the production of precipitates onto the biosensor surface, resulting in a significantly decreased photocurrent. Based on the plasmonic [email protected]@CDs nanoenzymes coupled with Ti2C/Ag2S composites, microRNA-155 was ultrasensitively detected with a wide linear range (1–10,000 fM) and a low limit of detection (0.83 fM). Moreover, the engineered plasmonic [email protected]@CDs nanoenzymes offer an environmentally friendly and multifunctional signal amplifier for fabricating PEC biosensor and have potential applications in biomarkers detection and disease diagnostics. 

Engineering of multifunctional carbon nanodots-decorated plasmonic Au@Ag nanoenzymes for photoelectrochemical biosensing of microRNA-155

Thymidine kinase 1 messenger RNA (TK1 mRNA) is an attractive biomarker that plays an important role in the cancer diagnosis and prognostic treatment. Herein, an ultrasensitive and selectivity photoelectrochemical (PEC) biosensor is proposed for TK1 mRNA detection based on the multicomponent Cu@Cu 2 O@C hybrid-induced photocurrent polarity switching of titanium dioxide nanoparticles (TiO 2 NPs). The multicomponent Cu@Cu 2 O@C hybrid with porous structure and specific surface area is successfully synthesized through the carbonization of copper metal organic frameworks (Cu-MOFs) in a nitrogen atmosphere, followed by the spontaneous oxidation of Cu. Through the TK1 mRNA-mediated chain displacement reaction, the Cu@Cu 2 O@C hybrid is introduced into the TiO 2 NPs-modified electrode surface, resulting in the photocurrent polarity switching from anodic to cathodic photocurrents. Originating from high porosity, specific surface area, multicomponent synergistic effect, and efficient photocurrent-polarity-switching capability of the Cu@Cu 2 O@C hybrid, the constructed PEC biosensor for TK1 mRNA detection shows a wide linear range (1–5000 fM) with a lower detection limit (0.59 fM), and excellent anti-interference ability. Furthermore, the designed multicomponent Cu@Cu 2 O@C hybrid serves as an excellent photocurrent polarity switcher for constructing a PEC biosensor, and may have great potential in biological analysis and clinical diagnosis. • Cu@Cu 2 O@C hybrid was designed as an excellent multicomponent photocurrent-polarity switcher. • An ultrasensitive photoelectrochemical biosensing strategy was proposed for the detection of TK1 mRNA. • The anti-interference photocurrent polarity switching strategy could eliminate false positive or negative results. 

Huimin Liu

Papers

A dual-model “on-super off” photoelectrochemical/ratiometric electrochemical biosensor for ultrasensitive and accurate detection of microRNA-224

Two-dimensional Ti2C MXene-induced photocurrent polarity switching photoelectrochemical biosensing platform for ultrasensitive and selective detection of soluble CD146

Amorphous carbon engineering of hierarchical carbonaceous nanocomposites toward boosted dielectric polarization for electromagnetic wave absorption

Engineering of multifunctional carbon nanodots-decorated plasmonic Au@Ag nanoenzymes for photoelectrochemical biosensing of microRNA-155

Multicomponent Cu@Cu2O@C hybrid-induced photocurrent polarity switching biosensing strategy for the detection of TK1 mRNA