News

November 2024

Publication - Ultrafast Carrier and Lattice Cooling in Ti₂CT_x MXene ThinFilms

Congratulations to Tong Wang, our senior PhD student, who recently got his research work published. In his work, he applied ultrafast laser spectroscopy across a broad time range (femto- to microseconds) to study the cooling dynamics of electrons and lattice in emerging Ti₂CT_x thinfilms compared to widely studied Ti₃C₂T_x thin films. The carrier cooling time in Ti₂CT_x is persistently ∼2.6 ps without a hot-phonon bottleneck. After hot carrier cooling is completed, the transient absorption spectra of Ti₂CT_x MXene can be described well by the thermochromic effect. Heat dissipation in MXene thin films occurs over hundreds of nanoseconds with thermal diffusivities ∼0.06 mm² s^–1 for Ti₂CT_x and ∼0.02 mm² s^–1 for Ti₃C₂T_x, likely due to inefficient interflake heat transfer. These results unravel the energy dissipation dynamics in Ti₂CT_x films, showcasing potential applications in energy conversion.

For more details, please find our publication here: Ultrafast Carrier and Lattice Cooling in Ti₂CT_x MXene Thin Films

September 2024

Chengning Yao won Young Researcher Award at EMRS2024

Congratulations to Chengning Yao, our senior PhD student, who has been awarded the Young Researcher Award at the EMRS-2024 Fall meeting.

July 2024

Publication - Thermally Conductive Hexagonal Boron Nitride/Polymer Composites for Efficient Heat Transport

Congratulations to Chengning Yao, our senior PhD student, who recently got her research work published. She proposed a cellulose-based composite embedded with few-layer hexagonal boron nitride (h-BN) flakes, achieving a thermal conductivity of up to 21.7 W m⁻¹ K⁻¹. This value is five times higher than that of bulk h-BN embedded one and is promising as thermal pastes for thermal interface materials for heat dissipation of electronic devices. The work demonstrated a clear advantage by showing that the few-layer h-BN embedded composite can reduce the maximum temperature of a heating pad at h = 2.48 W cm⁻² by ~ 24.5 °C, and reduce the maximum temperature by 9 °C of an operating high-power LED chip, than what bulk h-BN composites can do at the same h-BN loading. The results provide an effective approach to improving the thermal conductivity value of cellulose-based composite materials for heat dissipation in integrated circuits and high-power electronic devices.

Image is copied from https://onlinelibrary.wiley.com/doi/10.1002/adfm.202405235. For more details, please find our publication here: Thermally Conductive Hexagonal Boron Nitride/Polymer Composites for Efficient Heat Transport

June 2024

Dr Felice Torrisi won Harrison-Meldola Early Career Prize

Dr Felice Torrisi, from the Department of Chemistry, has won a Harrison-Meldola Early Career Prize for innovative contributions to the understanding of charge transport in networks of two-dimensional materials to develop printed electronics. In addition to this, Dr Torrisi wins £5,000 and a medal.

Dr Torrisi's work is groundbreaking in studying the physical mechanisms responsible for electricity transport in printed two-dimensional materials. His research includes using solution processing techniques and electrochemical synthesis to create functional polymer composites and advanced printable and sprayable inks for wearable electronics, quantum computing, and optimising electronic devices.

After receiving the prize, Dr Torrisi said: “I am thrilled to be awarded the Harrison-Meldola Prize. I am grateful to the collaborators and funders who supported my work, and I am so proud of the research group I am working with daily.”

December 2023

Christmas dinner 2023

We had a warm and happy Christmas dinner gathering at Le Petit Citron on 15 December, 2023. We have been growing into a larger group! 

Many thanks to Xinran for organizing this fantastic event! Thanks for wine from Felice.

Publication - Ti3C2 MXene as Additive for Low-Cost Textile Supercapacitors with Enhanced Electrical Performance

Textile-based energy storage components are paramount for establishing invisible electronic textiles that do not require conventional rigid batteries. A novel and scalable fabrication method is reported for introducing MXene (Ti3C2Tx) into activated carbon (AC) supercapacitors to enhance electrochemical performance. Supercapacitors are prepared within a single layer of textile with a phase-inverted polymer membrane fabricated within the textile yarn structure to form a porous, flexible, and mechanically durable separator. MXene is introduced in two different forms: 1) A multilayer MXene (m-MXene)powder is mechanically mixed with an AC slurry and deposited onto the textile. 2) Delaminated MXene (d-Mxene) nanosheets are spray-coated onto the surface of spray coated AC electrode. With an organic electrolyte, 1 M tetraethylammonium tetrafluoroborate in dimethyl sulfoxide, these supercapacitors are electrochemically stable between +/− 2.6 V and demonstrate a maximum areal capacitance of 148.7 mF cm−2, an energy density of 0.921 mWh cm−2, and a power density of 1.01 mW cm−2. The addition of MXenes improves the areal capacitance and by combining both approaches an improvement of 220% is achieved compared with identical supercapacitors with standard AC electrodes. The novelty of this work is to develop a scalable and straightforward solution processing method for introducing MXene into carbon supercapacitor electrodes enabling high-performance textile-based energy storage devices.

Image is copied from https://doi.org/10.1002/admt.202301266. For more details, please find our publication here: Ti3C2 MXene as Additive for Low-Cost Textile Supercapacitors with Enhanced Electrical Performance

March 2023

Publication - Hot Carrier Cooling and Trapping in Atomically Thin WS2 Probed by Three-Pulse Femtosecond Spectroscopy

Transition metal dichalcogenides (TMDs) have shown outstanding semiconducting properties which make them promising materials for next-generation optoelectronic and electronic devices. These properties are imparted by fundamental carrier–carrier and carrier–phonon interactions that are foundational to hot carrier cooling. Recent transient absorption studies have reported ultrafast time scales for carrier cooling in TMDs that can be slowed at high excitation densities via a hot-phonon bottleneck (HPB) and discussed these findings in the light of optoelectronic applications. However, quantitative descriptions of the HPB in TMDs, including details of the electron–lattice coupling and how cooling is affected by the redistribution of energy between carriers, are still lacking. Here, we use femtosecond pump–push–probe spectroscopy as a single approach to systematically characterize the scattering of hot carriers with optical phonons, cold carriers, and defects in a benchmark TMD monolayer of polycrystalline WS2. By controlling the interband pump and intraband push excitations, we observe, in real-time (i) an extremely rapid “intrinsic” cooling rate of ∼18 ± 2.7 eV/ps, which can be slowed with increasing hot carrier density, (ii) the deprecation of this HPB at elevated cold carrier densities, exposing a previously undisclosed role of the carrier–carrier interactions in mediating cooling, and (iii) the interception of high energy hot carriers on the subpicosecond time scale by lattice defects, which may account for the lower photoluminescence yield of TMDs when excited above band gap.

Image is copied from https://doi.org/10.1021/acsnano.2c10479. For more details, please find our publication here: Hot Carrier Cooling and Trapping in Atomically Thin WS2 Probed by Three-Pulse Femtosecond Spectroscopy

January 2023

 Publication - A sprayed graphene transistor platform for rapid and low-cost chemical sensing

We demonstrate a novel and versatile sensing platform, based on electrolyte-gated graphene FETs, for easy, low-cost and scalable production of chemical sensor test strips. The Lab-on-PCB platform is enabled by low-boiling, low-surface-tension sprayable graphene ink deposited on a substrate manufactured using a commercial printed circuit board process. We demonstrate the versatility of the platform by sensing pH and Na⁺ concentrations in an aqueous solution, achieving a sensitivity of 143 ± 4 μA per pH and 131 ± 5 μA per log₁₀Na⁺, respectively, in line with state-of-the-art graphene chemical sensing performance.

Image is copyed from: DOI https://doi.org/10.1039/D2NR05838C3. For more details, please find our publication here: A sprayed graphene transistor platform for rapid and low-cost chemical sensing.

December 2022

Benji presents his GFET research on MRS 2022

One of our senior PhD candidates, Benji Fenech-Salerno, attended MRS 2022 in Boston, USA earlier this month, where he was presenting his latest progress on 2D-material chemical sensors. He enjoyed the conference with fatanstic speeches and academic conversations very much.

Christmas dinner 2022

We had a warm and happy Christmas dinner gathering at Balans West on 9 December, 2022. Very nice dishes! After pandemic, it is so nice to have everyone in person and enjoy time together over meal!

Many thanks to Shuwei for organizing this fantastic event!

 Publication - Review of recent progress on free-standing supercapacitors

We summarize the recent progress on free-standing supercapacitors from new methods to create free-standing electrodes to novel applications for these devices, together with a detailed discussion and analysis on their electrochemical performance and physicochemical and mechanical properties. Furthermore, the potential directions and prospects of future research in developing free-standing supercapacitors are proposed.

Image is copyed from: Latham KG, Edathil AA, Rezaei B, Liu S, Nguyen S, Keller SS, Torrisi F, Greenhalgh ES, Titirici Met al., 2022, Challenges and opportunities in free-standing supercapacitors research, APL Materials, Vol: 10, Pages: 110903-110903.

For more details, please find our publication here: Challenges and opportunities in free-standing supercapacitors research.

November 2022

Chengning wins best student paper on E-textile 2022

Our very own Chengning Yao was awarded the best student paper at E-textiles 2022 Conference in Nottingham in November 2022! Chengning gave her 2-minute pitch and a wonderful poster presentation highlighted some of her key findings from her PhD work on the thermal conductivity of h-BN-assited composite. 

July 2022

Benji wins 1st at Chemistry PG symposium 2022

Congratulations to 1 of our PhD students Benji Fenech Salerno, who was awarded 1st prize in the Materials & Molecular Design Session in the Departmental of Chemistry PG Symposium in July at Imperial College London for his presentation showcasing our latest progress in biosensor research!

In his research, he demonstrated printed graphene field effect transistor (GFET) biosensors for the detection of multiple analytes, using reliable liquid phase exfoliation and repeatable printing technique.