Prof. Saad M. Alshehri

I am working as Professor of Inorganic Chemistry at College of Science, King Saud University, Riyadh, Saudi Arabia, previously I was the dean of the Riyadh Community College at King Saud University in Riyadh, Kingdom of Saudi Arabia. I have my received B.Sc. from King Saud University in 1984, and M.Sc. from Northeastern University, Boston, MA, USA. In 1989. I had received his Ph.D. in Inorganic Chemistry from the Leicester University, Leicester, LE1 7RH, England in 1992. I worked at Northeastern University, Boston and the Leicester University as a post-doctoral fellow. Prior to returning to King Saud University, Saudi Arabia.

RESEARCH INTEREST: 
My research is focuses on the construction of nanostructured, organic-inorganic hybrid materials for various applications. Understanding of the growth of nanostructures and designing novel materials such as organic-inorganic hybrid, gel-nanoparticles, liquid crystal and carbon nanoparticles is our main interest. Our research work addresses four major themes related to the applications of materials:-

Research in nanotechnology is undergoing a paradigm shift. A bottom-up or self-assembly approach is being investigated as an alternative to the current top-down approach. Most significantly, the shift from the exclusive use of lithography for device fabrication opens the field to not only novel fabrication schemes but the incorporation of diverse material systems.

Current and Future Research Interest (Energy Storage and Conversion)

1. Metal nanoparticles and nanocomposites as Electro catalyst:

        Controlling the size and structural morphology of noble metal nanoparticles on carbon supports is an interesting area of electrocatalytic research. Controlled structures are essential for achieving efficient catalytic activity to promote oxidation and reduction reactions in fuel cells. Currently, we are working on shape controlled platinum and palladium catalyst synthesis via electrochemical deposition technique. Pt and Pd catalysts with three dimensional dendritic and flower morphology were obtained using cyclic voltammetry and constant voltage techniques directly on carbon based supports such as carbon black, carbon nanotubes, wood apple shell carbon and graphene. Pt and Pd dendrites/flowers synthesized by the electrochemical methodology is free of template or surfactant, which also showed increased surface area and displayed increased electrocatalytic activity towards methanol/formic acid oxidation and oxygen reduction reaction in comparison to conventional Pt or Pd deposit. Electrodeposition with controlled coverage is also being carried out on carbon coated carbon paper generally used as gas diffusion layer in fuel cells. The prime interest is to control the morphology of Pt and Pd by altering the nucleation and growth mechanism.

2. Metal-free Catalysts for High Performance Oxygen Reduction

Oxygen reduction reaction (ORR) is the key process in many applications such as low-temperature fuel cells, lithium-air batteries and oxygen detectors, etc. However, the high price and sluggish kinetics of the currently available Pt based catalysts has made these energy conversion devices hard for commercialization or industrialization. Increasing studies have been conducted on the exploration of metal-free catalyst which is expected to be cheap, stable and comparably active as Pt for ORR.

According to the quantum theory simulation, carbon frameworks decorated with heteroatoms can provide non uniform electron distribution, which can help adsorb O2 and reduce them into OOH- or OH- electrochemically. Inspired by this, we have done a series of works focused on the novel porous carbons decorated with multiple heteroatoms (N-S, or N-B) or other metal-free active materials (graphite carbon nitride, g-C3N4) as catalyst for ORR. The resultant materials show very good catalytic performance for ORR and they also possess outstanding long-term durability and complete tolerance to fuel cross-over effect. All these excellent features make our materials promising candidates in the next generation energy devices. These works shed light on further research on the design, synthesis and evaluation of metal-free catalyst for the energy conversion and storage.

3. Carbon and metal oxide based materials for electrochemical supercapacitors

Electrochemical capacitors utilize activated carbons for both their positive and negative electrodes and show a non-faradaic, double-layer charging–discharging mechanism in a symmetric cell configuration. Thus, electrochemical capacitors are efficient energy storage devices that exhibit long lifespans and extremely rapid charge–discharge characteristics compared with batteries. Today, capacitor technology is regarded as a promising avenue and has an additional advantage of increasing effectiveness when combined with solar and wind regenerative energy sources. Normal battery–capacitor hybrids employ high-energy/sluggish redox electrodes and low-energy/fast double-layer electrodes, possibly producing a larger working voltage and higher capacitance. Energy storage mechanisms of electrochemical supercapacitors include double layer capacitance arising from the charge separation at an electrode/electrolyte interface and pseudo capacitance arising from reversible Faradaic reactions. My research has been focused on the development of electrode materials, which have high specific capacitance in various electrolytes. To realize a high capacitance, electrode materials are fabricated in a three-dimensional matrix form to achieve a high surface area. Novel electrochemical technologies are currently under development for the fabrication of nanostructured oxides and nanocomposites for applications in supercapacitors and hybrid supercapacitor-battery devices. An advanced testing facility is used for the investigation of power-energy characteristics and charge storage mechanisms.

4. Photocatalyst for H2 production, CO2 reduction and photodegradation of organic pollutants

Photocatalysis, as a green and sustainable technology, has attracted considerable interest due to being able to simultaneously tackle the energy crisis and environmental contamination by using solar energy. Photocatalysis technologies consist of photocatalytic oxidation and photocatalytic reduction. In theory, if we could combine photocatalytic oxidation with photocatalytic reduction in a photocatalytic system, the quantum efficiency and the separation efficiency of photo-generated holes and electrons would be markedly improved, which would result in excellent degradation of organic pollutants and good energy utilization. Until now, our group has developed a composite catalyst with good photocatalytic performance of degradation of organic pollutants coupled with simultaneous CO2 reduction demonstrating the combination of photocatalytic oxidation and photocatalytic reduction can be fulfilled in a catalytic system.