The Solar Coatings Group has access to a suite of materials synthesis and characterisation equipment, including three purpose-built chemical vapour deposition reactors for the fabrication of solid-state materials (with one capable of combinatorial materials synthesis), a range of hydro/solvo-thermal autoclaves and muffle furnace for producing nanopowder photocatalysts, thin-film XRD and Raman spectroscopy for their structural characterisation, profilometry and atomic force microscopy for their topographical characterisation and UV-visible spectroscopy for their optical characterisation, etc. Through collaboration, the group has access to state-of-the-art facilities for measuring time-resolved charge carrier behaviour in their semiconductor materials. The group also has access to state-of-the-art SEM, HR-TEM, XPS, etc facilities available to all research groups at Imperial College London.
Materials synthesis
The Solar Coatings Group has access to general wet-chemistry apparatus (e.g. sol-gel synthesis, co-precipitation, Schlenk lines, etc.), typical of any materials synthesis lab. We also have access to unique equipment, detailed below.
Chemical vapour deposition (CVD) - Lab B01, MSRH
Our CVD apparatus is of a bespoke, purpose built design, capable of operating in traditional atmospheric pressure CVD (APCVD) and aerosol-assisted CVD (AA-CVD) modes. It comprises of:
Our CVD apparatus, which can operate in APCVD and AA-CVD modes
4x two-wire AC cartridge heaters inserted inside individual aluminium blocks (& clipped to an insulating board) for the purposes of heating an amount of fluoropolymer tubing.
A Raspberry Pi configured as a Proportional Integral Derivative (PID) controller and 4x mains relay housed in a purpose built enclosure to control power to the above cartridge heaters and thereby provide invariant temperature control to said fluoropolymer tubing.
A K-type thermocouple mounted on the outer surface of the aluminium block to provide an accurate surface temperature measurement for the PID controller.
A multiplexed thermocouple data logger for digitising 4x thermocouples, and connected to RPi.
A CVD reactor, with the capacity to hold substrates ~6 x 14 cm in area (and typically up to ~0.5 cm thick), that can operate at temperatures up to 600 °C
Combinatorial atmospheric pressure chemical vapour deposition (cAPCVD) - Lab 402, FC L417, MSRH
The cAPCVD apparatus is a specialised piece of equipment that can be used to create inhomogeneous thin film coatings, with varying thickness and composition across the surface of the substrate. This facilitates the growth of a library of different materials in a single deposition, which can then be studied using high-throughput analytical methods, and therefore increase the speed in which thin film materials can be discovered and optimised for a specific purpose.
The cAPCVD apparatus; with 3 x temperature controlled bubblers with separate inlets into the reaction chamber
It has a CVD reactor, with the capacity to hold substrates ~6 x 14 cm in area (and typically up to ~0.5 cm thick), that can operate at temperatures up to 600 °C. It has 3 discrete bubblers with pipework that can direct precursors from these bubblers to 3 discrete locations at the baffle manifold before entering the reactor. Each bubbler can be operated at a temperature of up to ~360 °C. The pipework that connects these bubblers to the baffle are heated with heating wrap and can be operated at temperatures of up to ~200 °C. Only a single type of carrier gas, currently either air or dinitrogen, can be used in this system.
The hydrothermal bomb we use in our work is from Parr. They come with a batch Declaration of conformity, they are PED standard engineering practice vessels, and designed under the ASME code. The product has the following ratings:
• Body: stainless steel body with 6 six cap screws in the screw cap to seal the flanged PTFE cup • Liner: PTFE (Poly Tetra Fluoroethylene: Highly chemically resistant. Resistant to Acid and Alkali, and various organic solvents) • An expandable wave spring maintains continuous pressure on the seal during the cooling cycle when PTFE parts might otherwise relax and leak. • A safety blow-off disc above the PTFE cup will release pressure through an opening in the vessel head if pressure should accidentally reach the 3500 psi range (240 bar). • For safe operation, pressures in these vessels should never exceed 1900 psi (130 bar) and temperatures must not exceed 250 °C. • For heating these vessels we use an oven (Heraeus B12 Incubator Function), with a temperature limiter set to 240 °C to prevent overheating of the Parr bomb.
We have a general purpose muffle furnace, used for sol-gel synthesis reactions, solid-state synthesis, and annealing/ heat treatment of our coatings. The muffle furnace is a Nabertherm L9/11, with flap door and a B410 controller. Its technical characteristics are outlined below:
Horizontal sample orientation, with drop down door
Single heating zone
Maximum temperature: Up to 1100°C
Internal capacity: 9 L
Internal dimensions: 240 x 230 x 170 mm
Single phase 230V power supply
Materials characterisation
Thin-film/ powder XRD - Lab B05, MSRH
Bruker D2 Phaser X-ray diffractometer
The Solar Coatings Group maintains a Bruker D2 PHASER thin-film/ power X-ray diffractometer. The D2 PHASER is equipped with an integrated PC and a flat screen monitor. It is equipped with a LYNXEYETM compound silicon strip detector. The technical characteristics are outlined below:
• Geometry Theta / Theta (sample remains horizontal) • Max. useable angular range -3 … 160 ° 2Theta (depending on detector) • Accuracy ± 0.02° throughout the entire measuring range • Achievable peak width < 0.05° • Cu Kα X-rays from a standard ceramic sealed tube • X-ray generation 30 kV / 10 mA • Detectors Scintillation counter, 1-dimensional LYNXEYE • Single sample stage for 51.5 mm Ø sample rings • Sample motion spinning with user defined speed • Qualitative phase identification in EVA from the ICDD PDF2 database
The Air Pollution Simulation Chamber for measuring the photocatalytic activity of coatings and other building materials towards nitrogen oxides
The Solar Coatings Group has a purpose-built, state-of-the-art facility for examining the photocatalytic activity of materials towards nitrogen oxide gases. The facility is built in line with the specified ISO for examining photocatalytic materials towards nitric oxide (NO) gas (22197-1:2016), with the additional capability of studying nitrogen dioxide (NO2). The conditions inside the testing chamber can be adjusted to simulate an outdoor environment, where the pollution level, light source and intensity, humidity and wind speed can all be controlled.
Photoelectrochemical (PEC) testing station with incident photon-to-current (IPCE)
PEC testing station with IPCE measurement capability
The Solar Coatings Group has access to a PEC testing station with IPCE measurement capabilities. The set-up includes an optical stage, optics for controlling light power, a monochromator, a 75 W Xe lamp with KG3 filters for simulating solar light. We have various cells, electrodes and reference electrodes for measuring the PEC performance of photocatalysts for water splitting and CO2 conversion. We have access to a solar simulator light source, a monochromator, Clark electrodes/ gas chromatography and potentiostats for measuring device performance (e.g. JV curves, IPCEs, products formed and therefore the Faradaic efficiency of conversion, etc.)
