Improved Hydrogen Evolution Research Articles

First synthesis of RuSn solid-solution alloy nanoparticles and their enhanced hydrogen evolution reaction activity.

Solid-solution alloys based on platinum group metals and p-block metals have attracted much attention due to their promising potential as materials with a continuously fine-tunable electronic structure. Here, we report on the first synthesis of novel solid-solution RuSn alloy nanoparticles (NPs) by electrochemical cyclic voltammetry sweeping of RuSn@SnOx NPs. High-angle annular dark-field scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy maps confirmed the random and homogeneous distribution of Ru and Sn elements in the alloy NPs. Compared with monometallic Ru NPs, the RuSn alloy NPs showed improved hydrogen evolution reaction (HER) performance. The overpotentials of Ru0.94Sn0.06 NPs/C and Ru0.87Sn0.13 NPs/C to achieve a current density of 10 mA cm-2 were 43.41 and 33.19 mV, respectively, which are lower than those of monometallic Ru NPs/C (53.53 mV) and commercial Pt NPs/C (55.77 mV). The valence-band structures of the NPs investigated by hard X-ray photoelectron spectroscopy demonstrated that the d-band centre of RuSn NPs shifted downward compared with that of Ru NPs. X-ray photoelectron spectroscopy and X-ray absorption near-edge structure analyses indicated that in the RuSn alloy NPs, charge transfer occurs from Sn to Ru, which was considered to result in a downward shift of the d-band centre in RuSn NPs and to regulate the adsorption energy of intermediate Hads effectively, and thus enable the RuSn solid-solution alloy NPs to exhibit excellent HER catalytic properties.

On the origin of the improved hydrogen evolution reaction in Mn- and Co-doped MoS2.

In the field of hydrogen production, MoS2 demonstrates good catalytic properties for the hydrogen evolution reaction (HER) which improve when doped with metal cations. However, while the role of sulfur atoms as active sites in the HER is largely reported, the role of metal atoms (i.e. molybdenum or the dopant cations) has yet to be studied in depth. To understand the role of the metal dopant, we study MoS2 thin films doped with Co and Mn ions. We identify the contribution of the electronic bands of the Mn and Co dopants to the integral valence band of the material using in situ resonant photoemission measurements. We demonstrate that Mn and Co dopants act differently: Mn doping favors the shift of the S-Mo hybridized band towards the Fermi level, while in the case of Co doping it is the less hybridized Co band that shifts closer to the Fermi level. Doping with Mn increases the effectiveness of S as the active site, thus improving the HER, while doping with Co introduces the metallic site of Co as the active site, which is less effective in improving HER properties. We therefore clarify the role of the dopant cation in the electronic structure determining the active site for hydrogen adsorption/desorption. Our results pave the way for the design of efficient materials for hydrogen production via the doping route, which can be extended to different catalytic reactions in the field of energy applications.

Insights of the efficient hydrogen evolution reaction performance in bimetallic Au4Cu2 nanoclusters.

The design of efficient electrocatalysts for improving hydrogen evolution reaction (HER) performance using atomically precise metal nanoclusters (NCs) is an emerging area of research. Here, we have studied the HER electrocatalytic performance of monometallic Cu6 and Au6 nanoclusters and bimetallic Au4Cu2 nanoclusters. A bimetallic Au4Cu2/MoS2 composite exhibits excellent HER catalytic activity with an overpotential (η10) of 155 mV vs. reversible hydrogen electrode observed at 10 mA cm-2 current density. The improved HER performance in Au4Cu2 is due to the increased electrochemically active surface area (ECSA), and Au4Cu2 NCs exhibits better stability than Cu6 and Au6 systems and bare MoS2. This augmentation offers a greater number of active sites for the favorable adsorption of reaction intermediates. Furthermore, by employing X-ray photoelectron spectroscopy (XPS) and Raman analysis, the kinetics of HER in the Au4Cu2/MoS2 composite were elucidated, attributing the favorable performance to better electronic interactions occurring at the interface between Au4Cu2 NCs and the MoS2 substrate. Theoretical analysis reveals that the inherent catalytic enhancement in Au4Cu2/MoS2 is due to favorable H atom adsorption over it and the smallest ΔGH* value. The downshift in the d-band of the Au4Cu2/MoS2 composite influences the binding energy of intermediate catalytic species. This new catalyst sheds light on the structure-property relationship for improving electrocatalytic performance at the atomic level.

Nanoconfinement-induced water molecules and hydrogen molecules transport behaviors in ball-in-ball structure photocatalysts to improve hydrogen evolution

Nanoconfinement-induced water molecules and hydrogen molecules transport behaviors in ball-in-ball structure photocatalysts to improve hydrogen evolution

Modulating the electronic structure of MoS2 nanosheets by Mn doping for improving hydrogen evolution reaction: an experimental and theoretical DFT-QTAIM study

This study provides experimental and theoretical analyses of the effects of Mn doping on the electronic structure of MoS2 nanosheets and its impact on the performance of the hydrogen evolution reaction (HER). Experiments show that Mn doping alters the electronic structure of MoS2. This leads to an enhanced HER activity. The Mn-MoS2 nanosheets with a Mn/Mo molar ratio of 1:15 exhibit an overpotential of approximately 238 mV at a current density of 10 mA/cm2 and a low Tafel slope of 68 mV/decade in 0.5 M H2SO4. Density Functional Theory calculations and Bader analysis indicate that the incorporation of Mn atoms into the basal plane of MoS2 nanosheets activates all in-plane S atom sites and three Mo atoms neighboring the Mn dopant, thereby reducing the adsorption free energy of H atoms. Further, the Mn dopant enhances the intrinsic electronic conductivity of MoS2 by reducing its bandgap, which leads to a rapid charge transfer across the basal plane during H2 evolution.

Efficient fabrication of Ni-S/MoS2 hybrid nanoflowers for improved hydrogen evolution in acid media

It is significant to develop highly efficient and cost-effective hydrogen evolution reaction (HER) electrocatalysts. Herein, we propose an efficient fabrication of Ni-S/MoS2 hybrid nanoflowers grown on Ti foil (Ni-S/MoS2/Ti) via a simple one-step hydrothermal reaction method. When used as a HER catalyst, Ni-S/MoS2/Ti exhibits superior HER performances compared with MoS2 grown on Ti foil (MoS2/Ti) and Ni-S adsorbed on Ti foil (Ni-S/Ti) counterparts in acid media, due to its increased active surface area, enhanced electrical conductivity and synergistic effects from the coexistence of bimetallic sulfides. Additionally, Ni-S/MoS2/Ti demonstrates good HER durability, resisting the acid corrosion during HER process.

Effect of electron transfer of 2D Ti3C2Tx@MOF heterostructure on hydrogen evolution reaction activity

Metal-organic framework (MOF) layers were grown in situ from 2D transition metal carbides (MXenes, Ti3C2Tx) at room temperature to obtain the two-dimensional (2D) Ti3C2Tx@MOF heterostructures with a tightly connected interface. This interface provided more titanium atoms in the low-valence state in comparison to the original Ti3C2Tx, thus facilitating more electron transfer from Ti3C2Tx to MOF-(Fe/Co) nanosheets. The charge density difference and density functional theory results disclosed that Ti3C2Tx could modulate the electronic density around the active sites and lower ΔGH* energy barrier of 2D MOF-(Fe/Co) nanosheets towards the improved hydrogen evolution reaction (HER) activity. The obtained 2D Ti3C2Tx@MOF heterostructures exhibited a much higher HER activity in 1 M KOH electrolyte (with the overpotential of 104 mV at 10 mA/cm2 and Tafel slope of 79 mV/dec) than those of 2D Ti3C2Tx@MOF-TH, 2D MOF nanosheets, and Ti3C2Tx nanosheets. This research provides a basis for developing superior 2D MOFs, which can enhance HER properties through efficient electronic transport at the heterojunction interface.

Improved hydrogen evolution performance of Ni-based nanoporous catalyst with Mo and B co-addition

The exploration of efficient and stable noble-metal-free electrocatalysts for hydrogen evolution reaction (HER) is of great interest for the development of electrochemical hydrogen production technologies. Herein, nanoporous Ni-based catalyst with Mo and B co-addition (NiMoB) prepared by dealloying is reported as an efficient electrocatalysts for HER. The nanoporous NiMoB achieves an overpotential of 31 mV at 10 mA cm−2, along with exceptional catalytic stability in alkaline electrolyte. Density functional theory (DFT) calculations reveal that the incorporation of Mo and B can synergistically optimize the electronic structure and regulate the adsorption of HER intermediates on the Ni active site, thus accelerating the HER kinetics. This study provides a new perspective for the development of non-precious Ni-based catalysts towards efficient hydrogen energy conversion.

Influence of antisite defects on two-dimensional polymeric material for improved hydrogen evolution reaction

Two-dimensional materials (2D) supported by single atom catalysis have emerged as effective catalysts for H2 production at large scale by Hydrogen Evolution Reaction (HER). While there is a research surge on utilizing inexpensive metals as catalysts to replace Platinum (Pt) and other related noble metals, their practical limitations such as oxidation issues remain a concern. In this work, we report electrochemical HER activity of a recently synthesized metal-free 2D Polyaramid (2DPA) using Density Functional Theory (DFT) calculations. Pristine 2DPA exhibits remarkable HER performance in terms of active sites availability for hydrogen adsorption and the lowest Gibb's free energy change (−0.06 eV) close to that of benchmark Pt/C catalyst (−0.09 eV). Furthermore, introduction of antisite defects by substituting carbon for nitrogen (CN) and nitrogen for carbon (NC) in pristine 2DPA depicts enhanced HER activity. CN and NC defects tune the electronic properties by reducing the band gap resulting improved conductivity. Low formation energies calculated for obtaining antisite defects confirm their feasibility of synthesis while ab initio molecular dynamics (AIMD) simulations ensure their thermal stability at room temperature. The change in Gibb's free energy (ΔGH) values for CN-defective and NC-defective 2DPA are computed to be −0.13 eV and −0.11 eV, respectively. Both CN-defective and NC-defective 2DPA favor H2 evolution via Heyrovsky reaction pathways due to their relatively lower activation energy, 0.64 eV and 0.51 eV, respectively. Our findings encourage design and development of a novel 2D metal-free electrocatalyst for enhanced HER.

Ruthenium nanoparticles incorporated hollow carbon nanoshells for improved hydrogen evolution reaction

The development of efficient and stable catalyst is crucial for hydrogen evolution reaction (HER) in water electrolysis. The rational design of porous supports can effectively improve the exposure of active sites and increase the electrochemically active surface area of catalysts. In this study, a nanostructured carbon nanoshell (CS) is proposed for the synthesis of ruthenium and nitrogen incorporated carbon catalyst (CS@N-Ru) catalysts. Physicochemical characterization show that the prepared catalyst exhibits a hollow structure and abundant nitrogen/ruthenium related active sites, which enables the improvement of mass transfer and the catalytic activity. The electrochemical tests show that the prepared CS remarkably facilitates the performance of catalyst, the CS@N-Ru500 synthesized at 500 °C exhibits the best catalytic activity with a low overpotential of 35 mV at 10 mA/cm2 and Tafel slope of 38 mV/dec, attributing to the increased electrochemically active surface area, reduced electron/ion transfer resistance, and accelerated kinetics of HER. These findings suggest that the CS@N-Ru can be a promising alternative to Pt/C for HER in water electrolysis.

Enhanced photocatalytic hydrogen evolution over protonated g-C3N4 using NiCoP as a cocatalyst

Bimetallic phosphides as the cocatalysts have been demonstrated promising potential for boosting photocatalytic water splitting to produce hydrogen. Herein, a nickle-cobalt bimetallic phosphide (NiCoP) cocatalyst with flower-like structure built with nanoflakes in different directions is synthesized and self-assembled with protonated g-C3N4 (HCN) nanosheets through electrostatic interaction. The resultant NiCoP/HCN is employed for photocatalytic hydrogen evolution reaction. Benefiting from the excellent metallic conductivity and unique flower-like structure of NiCoP that offers abundant active sites, the NiCoP/HCN exhibits highly efficient separation of the photo-generated charges and greatly improved hydrogen evolution activity. The H2 evolution rate of the optimized NiCoP/HCN can reach 7951 μmol g−1 h−1, much higher than that of HCN nanosheets. The great potential of NiCoP for improving photocatalytic H2 evolution of g-C3N4 lights a valuable direction for exploring low cost and highly efficient non-noble metal cocatalysts for enhanced photocatalytic H2 evolution.

Optimizing Pt-Based Alloy Electrocatalysts for Improved Hydrogen Evolution Performance in Alkaline Electrolytes: A Comprehensive Review.

The splitting of water through electrocatalysis offers a sustainable method for the production of hydrogen. In alkaline electrolytes, the lack of protons forces water dissociation to occur before the hydrogen evolution reaction (HER). While pure Pt is the gold standard electrocatalyst in acidic electrolytes, since the 5d orbital in Pt is nearly fully occupied, when it overlaps with the molecular orbital of water, it generates a Pauli repulsion. As a result, the formation of a Pt-H* bond in an alkaline environment is difficult, which slows the HER and negates the benefits of using a pure Pt catalyst. To overcome this limitation, Pt can be alloyed with transition metals, such as Fe, Co, and Ni. This approach has the potential not only to enhance the performance but also to increase the Pt dispersion and decrease its usage, thus overall improving the catalyst's cost-effectiveness. The excellent water adsorption and dissociation ability of transition metals contributes to the generation of a proton-rich local environment near the Pt-based alloy that promotes HER. Significant progress has been achieved in comprehending the alkaline HER mechanism through the manipulation of the structure and composition of electrocatalysts based on the Pt alloy. The objective of this review is to analyze and condense the latest developments in the production of Pt-based alloy electrocatalysts for alkaline HER. It focuses on the modified performance of Pt-based alloys and clarifies the design principles and catalytic mechanism of the catalysts from both an experimental and theoretical perspective. This review also highlights some of the difficulties encountered during the HER and the opportunities for increasing the HER performance. Finally, guidance for the development of more efficient Pt-based alloy electrocatalysts is provided.

Non-covalent interaction of atomically dispersed dual-site catalysts featuring Co and Ni nascent pair sites for efficient electrocatalytic overall water splitting

The scarcity of highly effective and economical catalysts is a major impediment to the widespread adoption of electrochemical water splitting for the generation of hydrogen. MoS2, a low-cost candidate, suffers from inefficient catalytic activity. Nonetheless, a captivating strategy has emerged, which involves the engineering of heteroatom doping to enhance electrochemical proficiency. This investigation demonstrates a successful implementation of the strategy by combining ultrathin MoS2 nanosheets with Co and Ni dual single multi-atoms (DSMAs) grown directly on 2D N-doped carbon nanosheets (CoNi-MoS2/NCNs) for the purpose of improving hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). With the aid of a dual-atom doped bifunctional electrocatalyst, effective water splitting has been achieved across a broad pH range in electrolytes. The double doping of Co and Ni strengthens their interactions, thereby altering the electromagnetic composition of the host MoS2 and ultimately leading to improved electrocatalytic activity. Additionally, the synergistic effect between NCNs and MoS2 nanosheets provided efficient electron transport channels for ions and an ample surface area with open voids for ion diffusion. Consequently, the CoNi-MoS2/NCNs catalysts demonstrated exceptional stability and activity, producing low degree overpotentials of 180.5, 124.9, and 196.4 mV for HER and 200, 203, and 207 mV for OER in neutral, alkaline, and acidic mediums, respectively, while also exhibiting outstanding overall water-splitting performance, durability, and stability when used as an electrolyzer at universal pH.

Study on the hydrogen evolution performance of RuNi/TiO2-oxMWCNT catalyst in alkaline media

Hydrogen, as a clean and pollution-free energy with high calorific value, is one of the best alternatives to fossil fuels. Hydrogen evolution reaction (HER), as a half reaction of electrochemical water splitting, has also received extensive attention. At present, the development of low-cost and high-performance hydrogen evolution catalysts still faces enormous challenges. In this work, we synthesized a series of RuNi/TiO2-oxMWCNT catalysts with different Ru and Ni ratio. After optimizing the composition and proportion, RuNi/TiO2-oxMWCNT with Ru:Ni=4:6 has the optimal hydrogen evolution performance. High HER performance of extremely low 14.8 mV overpotential at 10 mA·cm−2 and 38.4 mV·dec−1 Tafel slope with perfect stability is achieved, which is superior to most reported ruthenium-based catalysts and even commercial Pt/C. XPS and UPS indicates that there is a metal synergistic effect of Ru and Ni and a strong SMSI between Ru and TiO2 in the RuNi/TiO2-oxMWCNT catalyst, which helps to improve hydrogen evolution performance. This study provides a pathway for the rational design of multi-component nanostructured catalysts for HER.

Discrepancy of alkaline/neutral hydrogen evolution activity from NiCoSe2/NC and Co–NiSe/NC derived from in-situ thermal and solution processing selenizations of ZIF-67

Constructing cobalt-based selenide catalyst with accessible active site and superior charge transfer capability by simultaneous tailoring chemical component and structure through the feasible strategy is the key to display improved hydrogen evolution reaction (HER) activity. Herein, the bimetal NiCoSe2/nitrogen-doped carbon (NC) with novel flake structure (NiCoSe2/NC/NF) and particle-like cobalt-doped NiSe/NC (Co–NiSe/NC/NF) were synthesized by the in-situ thermal and solution processing selenizations of ZIF-67/NF, respectively. The intrinsic catalytic activity of NiCoSe2, the further accelerated charge-transfer capability originated from the fresh NC and two-dimensional layer structure, and mutually reinforcing kinetics from the closely integrated NiCoSe2 nanoparticles and NC plate endow NiCoSe2/NC/NF with 141 and 284 mV to reach 10 mA cm−2 under alkaline and neutral electrolytes, respectively, accompanying with Tafel slope of 109 and 206 mV dec−1, which were obviously higher than that of the HER properties of Co–NiSe/NC/NF (η10 = 179 mV and Tafel slope of 127 mV dec−1 at alkaline condition, η10 = 301 mV and Tafel slope of 235 mV dec−1 at neutral condition). Meanwhile, the NiCoSe2/NC/NF and Co–NiSe/NC/NF were exhibited well electrochemical stability under alkaline/neutral conditions. This study offers practicable strategy for intuitive comparing the influence of selenization procedures on the whole alkaline/neutral HER activity of cobalt-based catalysts.

Improving hydrogen evolution catalytic activity of 2D carbon allotrope biphenylene with B, N, P doping: Density functional theory investigations

Using a first principles approach, we studied the hydrogen evolution reaction activity of newly synthesized biphenylene and B, N, P decorated biphenylene sheet. Hydrogen evolution reaction activity of pristine biphenylene sheet is not encouraging, as it is similar to pristine graphene. The Gibbs free energy and overpotential of P(N) doped on biphenylene sheet are 0.022 (−0.092) eV and 22 (92) mV, respectively. The reported Gibbs free energy and overpotential of Pt are 0.9 eV and 90 mV. Hence doping of P(N) atom on top of biphenylene sheet improves hydrogen evolution reaction activity much better (near to) Pt metal. We analyzed the adsorption mechanism of dopants (B, N, P) and hydrogen with Bader charge analysis and density of states analysis. P and N-decoration on biphenylene sheet change its electronic structure so that one obtains improved hydrogen evolution reaction activity for P and N-doped biphenylene sheet. Furthermore, the stability of N, P decorated biphenylene at room temperature with ab-initio molecular dynamics and formation energy near that of biphenylene indicate experimental feasibility. We have compared all our best hydrogen evolution reaction activity results in the reaction coordinate and volcano plots of pristine, B, N, and P-doped BPh sheets. They indicate that P-doped biphenylene is a metal-free, powerful catalyst for hydrogen evolution reaction activities.

Novel Sb2S3-xSex photocathode decorated NiFe-LDH hole blocking layer with enhanced photoelectrochemical performance

The alloyed Sb2S3-xSex has attracted widespread attention as a promising light absorbing material in recent years because it has the advantages of both Sb2S3 and Sb2Se3, such as adjustable band gap in the range of 1.1–1.8 eV and good stability. However, expensive selenourea enormously increases its manufacturing cost. In this paper, using Se powder as Se source, high-quality and low-cost Sb2S3-xSex film photoelectrode is successfully prepared by one-step hydrothermal method, and applied to photoelectrochemical (PEC) water splitting. Furthermore, with the help of NiFe-layered double hydroxide (LDH) modification, an increase in photocurrent density from −0.22 mA cm−2 to −1.21 mA cm−2 at 0 VRHE is achieved, and the onset potential is positively shifted by 120 mV. NiFe-LDH significantly improve hydrogen evolution reaction (HER) performance. The relevant characterization can confirm that this is mainly due to the blocking effect of NiFe-LDH on photogenerated holes, promoting effect of Ni2+ on the kinetics of hydrogen evolution reactions, and the strengthening of bulk charge separation efficiency. Undoubtedly, this work opens up a simple and effective way for the development of low-cost, high-efficiency antimony chalcogenides photoelectrodes, and provides new ideas for its excellent application in the field of PEC water splitting.

Photocatalytic H2 generation under blue and white LEDs by Fe2O3 /KTLO/rGO S-scheme composite photocatalyst

Photocatalytic water splitting using LED is of feasible approach for renewable energy enlargement. Alkali-titanates decorated with iron oxide at the molecular level was designed by a solvothermal reaction between prepared graphene oxide and K0.8Li0.27Ti1.73O4 with Fe (III) chloride. The reduced graphene oxide with iron oxide on alkali-titanates extends the effective way for its visible light harvesting. The effect of α-Fe2O3 loading on K0.8Li0.27Ti1.73O4/rGO was investigated towards photocatalytic water splitting, and achieving an improved H2-production rate. This present study will propose a new insight into the design and fabrication of layered titanate graphene-based photocatalysts using inexpensive α-Fe2O3 as a co-catalyst. The α-Fe2O3-K0.8Li0.27Ti1.73O4/rGO photocatalysts were characterized well by powder XRD, FT-IR, Raman spectroscopy, FESEM/EDS, High-resolution TEM, XPS, UV-DRS, and PL studies. Combining of heterostructured alkali-titanate photocatalyst leads broadening in optical absorption with a shift in the energy potential with acceleration in the interfacial charge transfer between α-Fe2O3 and KTLO, and rGO enhanced charge separation efficiency with remarkable hydrogen production rate. KTLO/rGO/Fe/5% (6200 µmol g−1) presents an improved hydrogen evolution rate around 29.5 times higher than bare KTLO (210 μmol g−1). A possible photocatalytic mechanism was proposed to elucidate better hydrogen production by using lactic acid as a sacrificial agent.

Construction of Ni4Mo/MoO2 heterostructure on oxygen vacancy enriched NiMoO4 nanorods as an efficient bifunctional electrocatalyst for overall water splitting

Despite great efforts over the past decade, rational design of bifunctional electrocatalysts with low cost and high efficiency still remains a challenge to achieve industrial water splitting. Herein, we synthesized the nickel-molybdenum nanorod array catalyst supported on NF (NMO@NM/MO) by a two-step process of hydrothermal and reductive annealing. Partial reduction of the NiMoO4 induces the structural reconstruction and formation of the Ni4Mo/MoO2 heterostructure on oxygen vacancy enriched nanorod, which bring out sufficient active sites, large specific surface area and favorable interfacial charge transfer. Thanks to the unique core–shell structure with the heterostructured Ni4Mo/MoO2 surface and defect-rich NiMoO4 core, the obtained electrocatalyst shows greatly improved hydrogen evolution reaction (HER) activity with an ultralow overpotential of 63 mV at 100 mA cm−2 (vs. 314 mV for the NiMoO4). Density function theory calculations reveal that the construction of the Ni4Mo/MoO2 heterostructure effectively accelerates H2O dissociation kinetics, while the defective NiMoO4 facilitates H* adsorption/desorption. Moreover, the heterostructure catalyst also displays excellent oxygen evolution reaction (OER) performance with the low overpotential of 274 mV at 100 mA cm−2. When coupling HER and OER by using NMO@NM/MO as both the cathode and anode, the alkaline electrolyzer delivers a current density of 10 mA cm−2 at only 1.50 V as well as good robustness. The synergistic effect of the hetero-interface and the defect engineering endows the electrocatalyst with excellent bifunctional catalytic activity for HER and OER. This work may provide a route for rational design of heterostructure electrocatalysts with multiple active components.

Doped MoS2 Polymorph for an Improved Hydrogen Evolution Reaction.

Green hydrogen produced from solar energy could be one of the solutions to the growing energy shortage as non-renewable energy sources are phased out. However, the current catalyst materials used for photocatalytic water splitting (PWS) cannot compete with other renewable technologies when it comes to efficiency and production cost. Transition-metal dichalcogenides, such as molybdenum disulfides (MoS2), have previously proven to have electronic and optical properties that could tackle these challenges. In this work, optical properties, the d-band center, and Gibbs free energy are calculated for seven MoS2 polymorphs using first-principles calculations and density functional theory (DFT) to show that they could be suitable as photocatalysts for PWS. Out of the seven, the two polymorphs 3Ha and 2R1 were shown to have d-band center values closest to the optimal value, while the Gibbs free energy for all seven polymorphs was within 5% of each other. In a previous study, we found that 3Hb had the highest electron mobility among all seven polymorphs and an optimal bandgap for photocatalytic reactions. The 3Hb polymorphs were therefore selected for further study. An in-depth analysis of the enhancement of the electronic properties and the Gibbs free energy through substitutional doping with Al, Co, N, and Ni was carried out. For the very first time, substitutional doping of MoS2 was attempted. We found that replacing one Mo atom with Al, Co, I, N, and Ni lowered the Gibbs free energy by a factor of 10, which would increase the hydrogen evolution reaction of the catalyst. Our study further shows that 3Hb with one S atom replaced with Al, Co, I, N, or Ni is dynamically and mechanically stable, while for 3Hb, replacing one Mo atom with Al and Ni makes the structure stable. Based on the low Gibbs free energy, stability, and electronic bandgap 3Hb, MoS2 doped with Al for one Mo atom emerges as a promising candidate for photocatalytic water splitting.