Dr. Deng research focuses on four key areas: 1) biomass based chemicals/hydrogen/biofuel/electricity, 2) cellulose nanomaterials, 3) nanostructured materials for electronic devices , 4) papermaking. His pioneer works include 1) a breakthrough invention of direct biomass fuel cell that can efficiently convert raw lignocellulosic biomass into electricity at low temperatures without using any noble metal catalyst; 2) low temperature conversion of biomass to hydrogen with extreme low energy consumption; 3) a record-breaking extreme sensitive ammonia gas sensor from polyaniline-TiO2 nanostructured p-n junction semiconducting material
- Biomass based chemicals/hydrogen/biofuel/electricity
Existing low temperature fuel cell technologies cannot directly use lignocellulosic biomass as a fuel because of lacking effective catalyst systems to break down the carbon-carbon bonds of the biomass – a natural polymer. In 2014, Deng’s group discovered a groundbreaking low-temperature fuel cell system that directly converts lignocellulosic biomass into electricity with assistance from a catalyst activated by solar or thermal energy. The system provides major advantages, including combining the photochemical and thermal biomass oxidation in a single chemical process, leading to high solar conversion and effective biomass degradation. It does not use expensive noble metals as anode catalysts because the fuel oxidation reactions are catalyzed by the POM in solution. Unlike noble catalysts, POM is chemically stable and therefore immune to poisoning by raw polymeric biomass. The hybrid fuel cell can use a wide variety of biomass sources, including starch, cellulose, lignin – and even switchgrass, powdered wood, algae and waste from poultry processing. The device could be used in small-scale units to provide electricity for developing nations, as well as for larger facilities to provide power where significant quantities of biomass are available. This invention has been licensed to a power company for scaling up testing. This work was first published in the journal Nature Communications in Feb. 2014. Dr. Deng further expended the biomass fuel cell work in 2015 and developed another new type of fuel cell by introduce two liquid catalyst system, which significantly improved the power density of the fuel cells. After that, his group has successfully applied the similar concept to sludge, coal etc. and directly converted these materials to electricity.
Dr. Deng’s work also focused on a novel electrolysis process that can convert raw biomass, such as grass and wood powders, to hydrogen in water solution at low temperatures (<100 C). The method is a simple one-step process without complicating pretreatment or purification. The electric energy consumption could be as low as 0.69 kWh per normal cubic meter of H2 (Nm-3 H2 ) at 200 mA cm-2, which is only 16.7% of the energy consumed for water electrolysis reported in literature. Unlike the traditional electrolysis of alcohols, noble-metal catalyst is not required for anode with this new chemical-electric conversion route. This chemical-electrolysis is a generic approach that can be used for most biomass.
Dr. Deng’s more recent work in biomass conversion focused on the chemical conversion of biomasses to high value chemicals. One example is to develop more effective catalyst systems for lignin depolymerization. Another example is to upgrade bio-oil by low temperature and high efficiency hydrogenation.
- Cellulose nanomaterials
Dr. Deng’s work in this area includes nanocellulose composites, unique aerogels for oil-water separation, absorption, supercapacitors, barrier packages, barrier films, hydrogels and drug delivery using nanocellulosic materials. He has published more than 30 papers related to cellulosic nanomaterials, and become an international leaders in this field. His invention on a novel oil-water filter based on nanocellulose aerogel has passed field test and has great potential for commercialization. He also focused on soft supercapacitors and solar cells based on nanocellulose materials for energy conversion and storage. Directly convert cellulose nanomaterials to carbon based electrode for hydrogen production is also one of his research area.
- Nanostructured material for electronic devices
One-dimensional nanostructured polyanilines, such as fibers, tubes and wires have been synthesized primarily by a template method or self-assembly via conventional chemical oxidative polymerization using both single-phase and interfacial polymerization routes. Dr. Deng developed a nanostructured ultrasensitive NH3 sensor. By uniquely assembling TiO2 and polyaniline hybrid nanofilms, this record-breaking NH3 sensor can detect 10 ppt (part per trillion) ammonia gas in air, (1000 time higher than any NH3 sensor reported previously). He also reported noble metal free carbon based catalyst for oxygen reduction and hydrogen evolution simultaneously.
- Pulping and Papermaking
Sponsored by DOE Industrial Energy Efficiency Grand Challenge program, Dr. Deng’s research team conducted a series of dry pulping studies. The dry pulping concept is an out of the box concept. His study confirmed that wood chips can be pulped by baking of chemically pretreated wood chips at ambient pressure without using high pressure digester. A significant reduction of the pulping chemicals was achieved using his dry pulping process compared with commercial Kraft pulping. Dry Kraft pulping at ambient pressure can reduce energy and pollution. One pulp company has adopted Dr. Deng’s technique and completed a pilot trial. The feasibility of the technique is under further review by the industry.